[993innc]

My opinion is buy any 993 you can afford. They are spectacular cars (I love mine) and are going up and going back to the mother land by the day. If you aren't mechanically inclined, buy the best one you can afford with the best documents possible (you'll pay dearly for it). If you aren't scared of working on it, buy whatever you want and it most likely will be a good car. OBD1 would be best so you don't have to deal with the SAI issue these cars have. But you're more likely to have the valve seal issue on the earlier cars. Look for white/blue smoke when running and warmed up, its the sign seals are bad.
The good thing is at least the issues 993's have don't grenade the motor from crappy inferior shaft bearings!!

964's are also coming up in value but still the bastard child of the 911 line. Heavy, slow and transitional between the coveted Carrera and awesome 993!

The 993 board over on Rennlist used to be the best group of guys I've found anywhere. Some of the old school patrons have disappeared but there's still a few knowledgeable guys around. Check it out if you haven't already.