I always liked the air cooled 911s myself because I remember playing with a MicroMachines 911[1] and they had all of the cool vents (which I guess are silly reasons), but man the new water cooled ones are fast. I think the eggplant headlight change from (I think) 97-01 was a bad move though. I'm glad they're back to the more traditional oval headlamps...
[1] http://www.toycollector.com/hwdphotos/uploads/1653/1691/Micr...