My build.....AR build anyways.

Optics will go on it. Right now in split between a short range scope with chambered sites and a eotech site. I have my eye on a bravo handguard similar to this but with a quad rail on the end.

Haven't heard about EOtech? Won't hold a zero in changing temperature conditions. Aimpoint or trijicon with a slight lead given to aimpoint for not making false claims (the MRO is not a true 1x and does have parallax at close ranges). It's so bad, they're actually refunding anyone who's ever bought one.

The BCM KMR is tough to beat, but if you want a free float quad rail there's really nothing with a comparable mounting method. They've all got issues that the KMR resolved.

I am a fan of the 'bootleg' rail though - they're licensing the BCM mounting method and it gives a short section of rail on the front end without making the handguard stupidly huge or sharp. I've got one and can say it's done pretty well. Pretty clever system.