As with anything, its really more a matter of personal choice and experience with them.
I prefer the Aimpoints. They are all expensive, then again, what would you trust your life to, a $100 Tasco, or a $385 Aimpoint? Is the difference between the Eotechs really even worth arguing over?
I find the Aimpoints a lot more natural and easier to shoot with. They tend to mount lower on the gun, give a normal cheek weld, and when I shoulder the rifle, the dot appears on the target just where I'm looking. I also like that I can keep the front cover closed and set the dot to one brightness so it doesnt wash out going from dark to light or vice versa. It also eliminates the need for a killflash(which drive me nuts anyway) and totally eliminates any flash from the front.
I always seem to be looking for the dot/reticule on the heads up type sights and then the target. They also usually sit to high, at least for me, making it hard to shoot naturally with and they are usually are harder to cowitness, if at all. With the Aimpoints, you can usually get them to cowitness with the right mount/ring.
Whats the battery life on the Eotechs these days? The Aimpoint M2's run 24/7 for about 10,000 hours and the M3's 50,000. I dont know why they even bother to put a switch on them, I just leave mine on. I do change all the batteries in everything in the house, twice a year, when I change the smoke alarms. I have yet to have to change an Aimpoint battery because it was dead though.