Hey, weren't you the guy who was really hesitant about the 360? Welcome to the darkside.
I haven't played alot of sports games yet. Madden is one I didn't like. Seemed too simplistic for me. Fight Night is probably the best sports game released so far.
I liked NFS: Most Wanted. Fun game but I get killed online. I liked Perfect Dark Zero alot. The online play was laggy though, I haven't tried it lately. Call Of Duty 2 is a must have for both single play and online. And Battlefield 2 is better for it's online play than it's single player game. Another good game, but not great like it's PC counterpart, is Far Cry. The graphics just aren't up to par for the 360 machine.