The discussion of how much parallax red dot sights have pops up all the time.  It gets very emotionally charged.  Measured parallax error gets converted to MOA.  Everyone knows that MOA is right around one inch.  Large parallax error in MOA at close distances looks like a huge problem.
What is frequently forgotten is that 1MOA is exactly one inch at only one distance: ~95.5 yards.
At closer distances, it is a lot less than an inch.

Here is a table that calculates linear parallax error at different distances for a given angular error in MOA:

One of the problems is that most manufacturers of red dot sights claim their sights are parallax free.  What they really mean by that is that they are parallax free in the sweetspot (some center region) at one particular distance (usually 40 or 50 yards).

EoTech, apparently and to their credit, actually posted some numbers that are about right based on what I have seen:

The only othe rhologrpahic sight on the market, Vortex UH-1 is slightly better than that at the edges.  However, with both EOTech and UH-1, I can only see parallax error fairly close to the edges.  Most of the center portion of the window has sufficiently low parallax error that the natural dispersion of my shooting completely conceals it.  

Suppose you are doing a CQB drill and go really fast.  You end up taking a shot where the aiming point is somewhere toward the edge of the window of the sight.  Worst case, you are picking up about 10MOA of error from the optic.  That is 1.5 inches at 10 yards.  Does that constitue a problem for a CQB scenario?  Not in the slightest.  The only time I can think of when it might be an issue is a hostage-type drill, but every time I have done it, there was enough time to roughly center the aiming point in the sigh tpicture.  That brings parallax error down to zilch and you get to concentrate on dealign with gun wobble, accelerated heart rate and general stress (and that assumes noone is shooting back at you).

As the distances increase, so does the magnitude of linear parallax error, assumign a fairly constant angular error.  However, I am rapidly getting past the point where I should be taking shots at anything much beyond two hundred yards without magnification (I will be hunting deer with an iron sight muzzleloader in the fall, so I will test this out in preparation).

If I am shooting at something 100+ yards away, chances are I will have an extra second to center the aiming point.

Now, none of this means that we should not check for parallax with our holographics and red dot sights.  However, what I care about the most is the size of the sweetspot: the center area of the sight picture where parallax is negligible.  As long as it is not too small, I do not get too hung up on the parallax performance at the edges.

Since I am pathologically late on everything, I figured I should release at least a summary as I try to put the final video content together.  I plan to do a livestream as a wrap up as soon as I organize all the data.  Below is a run down of a few categories.  Let me know if I missed something and I will add more detail.

I mentioned the whole reference standard idea about six months ago: https://darklordofoptics.locals.com/post/4249701/coming-soon-to-the-mailbox-near-you

The plan is to select a few scopes as my reference standards in a few categories and make sure I keep them on hand for at least the entire calendar year.  If they move on somewhere, I have to designate something else as the reference standard in that category.  There might be a couple of reference standard designs in each category to split them by price range.

Since I just went through the riflescope category exercise https://darklordofoptics.locals.com/post/5212669/riflescope-type-classification (the "reference standard" idea is one of the reasons I did that), let's stick with roughly the same framework.

Do keep in mind, that some categories I am not as well versed in as I'd like to be.  Also, there might be scopes in each category I consider exceptional, but do not have on hand.  Reference standard has to be something I have here and will use as a basis for comparisons.  I will endeavor to use optics that I believe to be at the top of their category, but it is not always possible.  Natirually, these will lean heavily toward mrad designs.  I avoid MOA like the plague whenever possible.

Fixed 1x
For prismatics, this has to be Primary Arms SLx 1x Microprism.  https://bit.ly/3uLqu0E I have a few different 1x prismatics on hand, but SLx is the only one that has been here long enough to be the standard for 2024.  For now.  There are some really interesting options in this range.

Fixed mag small prism
This can go in a variety of different directions depending on personal preferences and price.  It is not practical to have a reference standard for every magnification and with compact prismatics I do like 3x as a good compromise magnification.  These scopes are a step up from people who have been using red dots with magnifiers and want a better experience at distance.  This one will also go to Primary Arms.  Technically, I like GLx 2x more than SLx 3x, but 2x is such a unique magnification that it is not a very good yard stick for comparisons.  SLX 3x Microprism it is, then.  https://bit.ly/4bMMclz

Fixed mag large prism

Somewhat oddly, with large prism scopes, I start leaning toward higher magnifications.  I want these in 4x or 5x.  I view these differently.  These are, to me, alternatives to LPVOs and spiritual successors of old general purpose 4x and 6x fixed power scopes, except more compact and with wider FOV.  There a couple of good options and, unsurprisingly, my favourites are Element Immersive 5x30 https://bit.ly/3NjJ4mJ and the discontinued Elcan Spectre OS 4x.  The dual power Spectre DR is still thriving, as expensive as it is.  https://bit.ly/4bQpwAN  I have the single magnification 4x and it is a very good yardstick for what a high end prismatic should be.  With the Element, I am clearly biased since I designed the reticle for it.  In other words, I got to put a reticle I could not get other people to make into a scope I like.  You should not be terribly surprised to see it here.

LPVO

This one gets tough and there will be several options here.  Keep in mind that I like FFP LPVOs once we get up in price.

With budget LPVOs, for now, it is Primary Arms SLx 1-6x24 with Nova reticle. https://bit.ly/40LeLdt It has some competition this year, but until I spend more time looking through it, PA takes it.

On the mid-range, it is a battle between SAI6 1-6x24 with mrad reticle https://bit.ly/49Nomo4 and PA PLxC 1-8x24 with meters BDC reticle. https://bit.ly/3Bn3951  With PA, I am not a fan of their other reticles, but I like how light and short it is with an excellent eyepiece.  With SAI6, I like the whole reticle line-up but lean toward the mrad designs for general purpose use.  The X-Wing style high visbility feature is not for everyone, but it works for me.  I suppose I will keep both here.  

If you go up in price, my basic opinion has not changed.  Vortex Razor Gen3 1-10x24 is the one to beat if you want a nuclear bright reticle.  https://bit.ly/3w1Ah2T

This leaves a little of a "no-man's land" with LPVOs that are designed to be true general purpose designs, like the side focus equipped March Shorty 1-10x24 and Delta Stryker 1-10x28.  They are a little too different to serve as a useful yardstick for anything but each other.  For now.

Dangerous Game

I may have to skip one because I do not really have anything on hand right now that fits the description and I have had long enough to make it a reference standard.  I do have some ideas, so stay tuned.

MPVO

For the time being, the one to rule them all is the dual focal plane March 1.5-15x42 https://bit.ly/4bjm15X  This category, almost by definition, is the one where compromises are made for the most flexibility.  This March is not perfect, but it is the best we currently have.  On the budget end, the yardstick should be Athlon's excellent Helos BTR Gen2 2-12x42, but it is sitting on top of a friend of mine's rifle two states to the West.  It can't be a reference standard if it is not here.  In the meantime, the old reliable SWFA SS 3-9x42 will do.  I have a couple of them.  https://swfa.com/swfa-3-9x42-ss-hd-mil-quad-reticle-30mm-tube-1-mil-clicks-ffp/

Tweener

I do not like to use a discontinued scope as a yardstick, but Razor HD LH 1.5-8x32 has got to be it.  It is not a common scope category, so we will hoble along like this until I come up with something still manufactured (that fits the profile and I like).  On the low-ish end of the price range,  I do like SWFA 2.5-10x32 Ultralight and have a couple of them.  https://swfa.com/swfa-2-5-10x32-ss-ultralight-msr-556-bdc-reticle-1-tube-25-moa-clicks/ 

Crossover

For once, this one is easy and I'll keep it all within a sane-ish price range.  Vortex Razor HD-LHT 4.5-22x50 https://bit.ly/3KEbZyA and Delta Stryker 3.5-21x44 https://annexdefense.com/delta-stryker-hd-3-5-21x44-rifle-scope/ are the purest expressions of the crossover idea I have seen to date, this side of Tangent TT315M that you will see a couple of categories down.

Traditional Hunting

This get difficult again because it is not a type of a scope that is common around these parts and the ones I look at do not stick around too long.  I simply happen to be an FFP guy.  However, some hunting scope articles are very much overdue and I do have an excellent Delta Titanium 1.5-9x45.  In sticking with sane prices, let's add Tract Toric 2.5-15x44 with illuminated reticle to this list.  https://tractoptics.com/toric-uhd-30mm-2-5-15x44-ffp-illuminated-mrad-mrad-hunting-rifle-scope

These two should give me a decent ability to compare.  On the high end, there are several real interesting options, but I do not have any on hand since the two categories bracketing this one fill that role for me.

General Purpose Practical Precision

Given how much this crosses over with, oun intended, crossover designs above, I could have merged them into signle category.  It would make too much sense so here we are.  Tangent Theta TT315M 3-15x50 is still it to me. https://bit.ly/41dz6c8

In the less eye-wateringly expensive world, the current range of 4-25x50 (or thereabouts) designs from LOW seem to offer a lot for the money.  Tract's version is a good example.  https://tractoptics.com/toric-4-25x50-34mm-mrad-elr-rifle-scope

Moving further down in price, I think Burris XTR3i 3.3-18x50 takes the cake https://bit.ly/48ViwQX  I really like how capable it is at very near to $1k, so it will be here for a while.

Long Range Practical Precision

I might catch a lot of flack for this one, but so be it.  

High end: still Tangent Theta 5-25x56 https://bit.ly/3ORWU0n

Best bang for the buck on the high end: Vortex Razor Gen3 6-36x56  https://bit.ly/3VcAXJD

Mid-range: Delta Stryker 4.5-30x56 (there is a bunch of simlar scopes in this category and I happen to have this one)  https://www.edgunwest.com/store/delta-optics/item/delta-stryker-4-5-30x56/

Low-mid range: Meopta Optika6 5-30x56 (again, there are several to choose from that are similar, but this one is on hand) https://bit.ly/3Ia4QX9  and Delta Javelin 4.5-30x56.  There are some similarities between them, but these are not identical scopes  https://annexdefense.com/delta-javelin-4-5-30x56-rifle-scope-ffp-smr-1-do-2470/

Short Range Target: I'll have to skip this one for now.

Long Range Target: Ditto.  It is not a category I look at much, so I do not have anything on hand that will fit.  I will rectify that.  Until then, the best paper shooting scope I have and intend to keep is March 5-42x56.  It bridges several categories nicely since it is FFP, but it pulls target shooting duty for me.  If I decide to do a comparison review on target scope, this Marhc will serve as the reference standard.  https://bit.ly/3TdABox

Field Target: I do not have a Field Target setup, so this category is going to be skipped for now.  Hopefuly, not for too long.