Ive driven both and actually own a series II 96 JZA80 SZ-R with the factory getrag 6 speed box (very rare). Only minor mods i.e Buddy Club Fully adjustable coilovers, cat 2.5in back zaust, BBS rims with 265s on the back and still breaks traction (factory LSD) w/ 3.75 gears? I think lol, plus the best part about the SZ-R is the box, for those who know about the v160 getrag they are awsome (same as TT variant). They are very comfortable, but handle like a gokart when you wind the stiffness right up. In wa they arent very common which is also nice. Interior is different on series I and II, only little stuff though. Best part if you ever go turbo and have the six speed SZ-R its an easy swap and you dont have to worry about have a much much much weaker W58 box behind it.
That all being said, the back seat is really cramped, almost no point in having it. With that in mind the supra is a real drivers car, perfect on both the track and on the street, great styling and not to mention fuel consumption is great on a full tank depending on how you drive it I get 550+ kms out of it, but you will want to drive it all the time, the interior really does seem like that of a fighter jet.
Im not being biased here, Im actually a big skyline fan and like them more than the Supras.
Mines up for sale, only because I want a drift car you wont fault these cars, the 2JZGE is an awsome motor. Mines going for 14,500. Much cheaper than a man n/a 34.