Here is my canned answer that I always use:
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I have both, and they are both great. However, if I had to choose just one, it might have to be Eotech. But you really can't go wrong with either.
Advantages of Eotech:
- Eotechs are faster. That 65 MOA outer ring makes it easy to naturally place on target and his very fast. Nothing is faster.
- Eotech is cheaper. A Eotech 512 will run you about $350. A Aimpoint ML2 will run you about $480 (with mount).
- Eotech is more precise. The 1 MOA center dot of the Eotech is great for long range precision work. The 4 MOA dot on the Aimpoint will flood targets past 100 yards. Not a big deal if you are use to irons, and guys can still be accurate with irons, but I like my site to be smaller than my target.
- Eotechs is easier to use in the bright sunlight. Even if your Aimpoint has the 4 MOA dot, it takes a little extra concentration to see the dot, while it takes no effort to see the 65 MOA ring of the Eotech.
- Eotech has larger Field of View. This is nit pick as both are suppose be used with both eyes open, so Field of View is not an issue.
- Eotech you do not have to be inline. This is another nit pick. Both have infinite eye relief, but with the Eotech you can be off to the side a little and still be able to use it. With Aimpoint you have to be directly behind it like a magnified scope.
Advantages of Aimpoint:
- Aimpoint has Long Battery Life. You can leave the Aimpioint on for a whole year before the battery runs out (5 years if you have the M3 or ML3). You could throw the gun in the back crew cab of your truck with it on and forget about it, or turn it on before you go to bed and it will be ready to go at any time. Eotech says 1100 hours, but I don't know about that as I already have changed the battery on my Eotech twice and I don't even leave it on for extended period of time.
- Aimpoint Looks better. Nothing looks better on an M4 than an Aimpoint.... If you don't count ACOGs [

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- Aimpoint is more water resitant. Eotech claims water proof to 10 feet. Aimpoint claims 75 feet. I have not thrown either in the water to confirm this.
- Aimpoint is more rugged. This is arguable, but the Aimpoint just appears to be better built. Eotech appears it could be taken out with one good bang while I can't see any way to take out an Aimpoint.
Once you get use to one, it would be harder to like the other one. For me I switch frequently between the 2 so I am not really locked into just one. Good to be proficient in everything you possibly can, because when the SHTF, you never know what you are going to be stuck with.