I've played d20 Modern, and I like it on the whole, but there are certain rules that I start tearing my hair out over.
Anyone played any of the others? True20's version or Modern^20? Anything else I should look at?
I would say Mutants and Masterminds. Yes, it is a super hero game, but I think it also works well for a cinematic style modern game. Agents of Freedom is a must for this style.
I think True20 works well as is for modern campaigns as well.
I hope Pathfinder does a modern/sci-fi ruleset soon.