What you need from your red dot sight is clarity, ease-of-use, and reliability. The NcSTAR series of red dot sights offer that in spades and much more. For the purposes of paintball, an unlimited eye relief reflext sight like this one is generally going to be your most effective. You can target faster and use it with both eyes open and with the non-rifled nature of paintballs, you're going to be able to target more accurately at those shorter distances.

This particular sight features both Weaver and Dovetail rail mounting capabilities as well as a multi-position rheostat knob for red or green light illumination.