I loved Need for Speed 1 on the PS1 and later the the PC. It was amazing for me, coming from thinking Test Drive 2 on my Amiga was awesome...
NFS 2 was unfortunately released in the early era of shit 3D so it always looked horrible. IIRC it was also the last NFS game to have those super cool introduction videos for all the cars.
Hot Pursuit was incredible fun, and it was the game that made me buy my first force feedback Logitech steering wheel, but unfortunately looks awful today, too.
Underground was kinda fun because it was innovative but in the end it was really shit because it was a one trick pony that took away beautiful sportscars driving through beautiful, sunny scenery and replaced that with awful ricers street racing through a boring city at night.
Most wanted was kinda fun, but it was too brown and clinical, and the added on story was really horrible. Carbon was... well, a carbon copy of that, only set at night.
Everything after that was just forgettable and it pains me that this awesome series went so far down hill
I'd really really love a remake of the first game.