Each year of the P38A's had successive mods / improvements, and as ever the less mileage the less opportunity for mis-service etc to have occurred. Myself I'm more than happy with my '96 that I bought used a couple of years ago, although I have had to address some of the 'first model year' issues (like replacing the steering wheel with that from a '97, etc).
I believe the big model change was the 99 MY (Bosh electrics, 4-wheel traction control as opposed to the earlier models 2-wheel version, etc). So to my mind the 99 MY is probably as awkward a year as the '96 (ie first model year of setup). Another nice item on the 2000 MY are the external dimming rear view mirrors (the internal was auto-dim from start). Of course you'll probably end up paying extra on 2000 -> for the GPS system, which isn't the easiest / nicest to use, but at least it's there.
Overall I'd say not to worry too much about a specific model year, but rather worry more about proven maintenance records from either dealer or well-respected specialists, together with mileage. Each model year had it's own baby illnesses pretty much, with the earlier years you don't have to worry quite so much about the depreciation, and hopefully the previous owner(s) will have taken care of the issues whilst it was under warranty.
In any case, I would strongly suggest considering adding 2-3K to the final price for a good extended warranty, ideally the dealer one (but that means having to find a vehicle at a dearler...).
Having said all of that... personal favourite probably '98MY atm, followed by a tie for the 2001/2000. Then again I wouldn't part with my '96 [got to love $35 a year IA tax & title!].