Need for Speed 3, - Hot Pursuit. That game was my childhood. (Maximum air acheived using the ferarri spider on the hometown track in between the tunnels going backward)
Need for Speed 4 - was twice as awesome with twice as many cars and tracks as well as career mode for the first time and damage
Need for Speed 5 - had bess graphics for when it came out and the handling was a nice mix between realism and arcade. I used to win entire tournaments in that game without getting a scratch on my car because I couldn't afford to fix it. This game was just a big marketing ploy by porsche... and it worked
Need for Speed 6 Hot Pursuit 2 - was a fun with more arcade style handling but needing points to unlock stuff killed the feel of the game. It was fun but got bored for some reason.
NFS Underground/Underground 2/Most Wanted/ Carbon - Felt like NFS found a new niche. I didn't like the change at first but like many teenagers back then, it spoke to my teenage angst. I like each one more than the last... except Carbon... they should have stopped at most wanted
NFS Pro Street had extremely realistic handling and promoted road safety, track racing and boredom. Only played the first couple races.
NFS Undercover - I built my first PC from scratch just to run this game. I beat it about 5 times just to try out all the cars. This may not be the best NFS but it's the NFS that I have the fondest memories of. Downloaded the soundtrack and still play it when I'm driving with my small bro in the car. Good times... good times...
NFS Shift/Nitro - Got a job and didn't have chance to play
NFS World - Last NFS I ever played. Had online racing and in game chatting so it was fun to meet with friends and race when we got chance after work.