Vortex Strikefire. Hands down. For under $300.
I'd say for the extra bit of $$$, go for an Aimpoint Pro also. It's WELL worth it. I have a number of red dots and recently swapped out my Strikefire for a PRO M4 and I gotta say... Lighter, crisper dot even at higher intensities and my eye seems to be less bothered by distortion which leads me to think the glass is better. Plus, it takes AA batteries instead of ridiculous $20 CR123's, lol! I'll not be running my Strikefire in 3 gun this year, but keep in mind it's only because I upgraded. If it's going to be a long term investment optic, spent a bit more. You won't be disappointed.