If you are looking for something thats more drag racing oriented, try Need for Speed Pro Street. It doesnt have the open-world setting (some people like it, some dont) but the racing is better and more structured.
I had Carbon and still have MC:LA. Carbon seemed like it was Most Wanted, with a return to a night time setting. Kinda thrown together, i guess. Also, IIRC, there isnt and drag racing.
Midnight Club is cool, but it can be kind of a pain in the ass to get from race to race, cuz you have to drive there. There is no feature to go directly to it. And losing the cops can be a hassle as well.
I have heard that the newest NFS, Undercover, kind of blows. So i havent tried it yet. I just picked up Pro Street at Gamestop for $15 used, and i think its like $30 new.
let us know what you decide.
