I am kinda partial to the 2003 models.....especially since I had 1.
The 2003 had the aluminum frame, AC on the front shell (instead of the cabinet or rear shell), and round fender wells improvements that the older models didn't. That year also had the sewer hose bumper that the new models don't have. The big thing missing over the newer models was the accessibility of 110 volt power cord in the closed position.....and I remedied that with a modification.
Like Bill stated, the early 2000s brought a lot of changes, mostly for the good. We bought used, and got an excellent unit at a great price. I was not familiar with TMs at that time, and was actually planning on a 200 mile round trip to look at them at a dealer, when the missus saw an ad in the paper. I stumbled some when checking out the unit, and wish I was a member of this forum before buying. I would not be afraid to buy used especially using all of the advice on this forum on what to look for.
Buying a couple year old unit can save you $1000s. We bought our then 3 year old for a fraction of what the original owner paid new.