nfs most wanted, nfs underground. i liked nfs most wanted more than nfs underground because it gave you more of an objective in the game , and it was somthing out of the ordinary compared to the nfs games i have, and the ones ive seen my friends play
i ve played every NFS from Nfs2 upwards and think that undercover was one of the best(xbox) i personally didnt like nfs Pro street that much beacause i prefer acarde racers not simulations
I miss HP, HS, and HP2 (fast non-ricer cars in exotic locales with scenic views), but underground 1/2 and most wanted were nonetheless pretty good games. ProStreet was eh... not so much. Shift was like a halfway point between forza and prostreet, they should have gone all the way through to forza (ie, more simulator-like).
However, Criterion Games (makers of burnout series) is developing the next NFS which is Need for Speed: Hot Pursuit. Looks pretty promising from the trailers so far, looks like they're going back to the roots.