I really do love this forum. Very even handed answers. I am a previous MKIV TT owner and regret to this day every selling the car.
Just some history lessons for those asking where the .99 skidpad rating etc are, the Supra came very close IIRC did reach 99 in some tests.
I am too lazy to pull up the comparison. It finished second only to the NSX on a track day even against all the other 90s JDM super cars.
Also some interesting facts pulled from the WIKI..
The Supra was also lighter than the Mitsubishi 3000GT VR4 and the Nissan 300ZX Turbo. Despite its curb weight, in 1994 the MKIV managed a remarkable skidpad rating of 0.95 lateral g's (200ft) or 0.98 lateral g's (300ft) [1] due in part to a four-sensor four-channel track tuned ABS system with yaw control whereby each caliper is sensored and the brakes are controlled individually according to the speed, angle, and pitch of the approaching corner. This unique Formula One inspired braking system allowed the Supra Turbo to record a 70 mph (110 km/h) -0 braking distance of 149 feet (45 m) [2], the best braking performance of any production car tested in 1997 by Car and Driver magazine. This record was finally broken in 2004 by 3 feet (0.91 m) by a Porsche Carrera GT.
I assume you would be purchasing a Targa. I loved popping the targa off and going cruising. One thing the Z will never match is the pure joy of that smooth 3 liter Inline 6 in the Supra. Whenever I ride in my friends 335i I lust for that engine, because it is every bit as smooth and compelling at higher revs than the 335is..
The Supra is a collectible. The whole old car debate IMO is fairly irrelevant, aside from things like Nav and more interior features the car is very modern. As long as you can maintain it in a healthy state it's not going to be outclassed by much. If you stick with BPU, you are looking at a mid 12 second car with 115-118 traps, which used to be nearly world beating, is still very fast.
It's a very nice car just to drive around in when you are not completely trashing it. If you miss the 370 you can always pick one up used, your supra will hold its value.
I love both cars, but I will always hold a special fondness for the Supra. I had an absolute blast in that car, live the dream! The 370 isn't going anywhere and the Supra will only become more difficult to obtain as it gets older.