Where do you play? Most of the time a clone Aimpoint red dot will do for the majority of airsoft situations. Personally when I played outdoors I used an ACOG as I'm a bit short sighted and it was a huge boon for team ident, but otherwise you don't really need the magnification (or the associated weight) that glass brings.
I find all the EoTech clones have really bad reflection on the rear glass hence I'd personally go for a copy of an Aimpoint. The glass is often still very reflective but the window is much smaller so less of an issue. If you can I'd look at some red dots in person, that way you can check the glass. I've bought some cheap ACM optics before that had horrendous brown-tinted glass and gave a really terrible sight picture. If it's for an AEG (not electric recoil or gas) then you generally don't need to worry too much about exactly which one you pick.
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