I've owned an Aimpoint, shot with several different EOTechs, and handled/sighted through several ACOGs. Here are my impressions of each.
AIMPOINT: I prefer the mounting options of a tube-type sight; forward/back, up/down, all easy and lots of choices for mounts. I like flip-up caps; they're always there (no getting lost), and because they're there, you'll use them (not a pain like other options). Standard dot size is a good compromise, can be used at most reasonable ranges (as for target shooting, I've shot steel plates/dingers at 300+ yards with mine; as long as you have a good zero and can see the target, you can hit it). Durability and battery life is outstanding. Field of view is more limited than some other types of sights, although this is not as bad and as critical as some folks would have you believe, IMO.
EOTech: Smaller dot is better for smaller targets, assuming you can SEE the target; vision is the limiting factor here. Smaller dot does NOT make it possible to shoot farther or with more accuracy if you cannot see the target under field conditions. Mounting options are more limited than with the tube-type sights, and some owners/operators have reported problems with the mounting screw loosening regularly during use. Has battery type options; handy if you want to match sight to what you already stock/carry. I don't like the stretch neoprene cover at all, and that's pretty much the only option for lens protection. Quick power-on options are nice, but if you have moved from a very light to very dark area since last power-on, you're gonna have to futz with it for a few moments to get it adjusted. The rotating on/off/brightness knob on the tube-type sights seem to be quicker in these circumstances, but perhaps I just haven't used the EOTech enough to be well-trained in how to best use it. Great battery life, but a few durability problems (electronics?) have been reported in field use (dot just "goes out", sometimes for good).
ACOG: Nice, but you're stuck with whatever magnification you get; if it's too much or not enough, tough. You can add a magnifier to the dot sights, above, and get a little more versatility out of them over the ACOG, if you don't mind the extra bolt-on "stuff" required. Because the ACOGs magnify, you cannot use iron sights through the sight's tube in an emergency; you'd have to dismount the sight to use your irons. Lots of reticle choices, and a few colors, too. Eye relief on all models I've seen varies from short to REALLY short, and the rearmost lens is so far to the rear (and relatively unshielded) it can pick up reflections from around/behind you, which is distracting under some circumstances. Super durable, no batteries, but I've yet to hear how a person goes about getting the Tritium replaced when it dims, and how much that will cost. Due to integral see-through carry handle mounts on some models, these might be the best choice for vintage ARs with old-style uppers. Spendy; bring the checkbook. Can be difficult to find the exact one you want.
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Later on if I want to get an Aimpoint magnifying scope to put in front of the M2 I'll end up paying about the same as the Trijicon ACOG...
Thoughts, opinions...?
But you'll have a more versatile sight, usable at VERY close (spitting distance) range when bare, as well as way out yonder with the magnifier. And although the TOTAL money will be comparable, you can split the purchases up to make it less painful.
Have you considered the Leupold Prismatic dot sight?