As far as reliability goes, both versions of the Supra are pretty exceptional. You get horror stories about poor and abused examples, much like with any car, but in general a TT Supra is not volatile in the slightest. Plenty of people have them as daily drivers without issues. I've had mine for 18months or so and done around 12k miles without even a hint of an issue (except for a stupid garage giving me an oil leak). There are several on the forum that have done over 200k miles without any major failures.
While the N/A isn't supercar quick, it's not exactly slow. As far as I'm aware (although this is a much debated issue) 0-60 on the N/A is around 6.5-7s and on the TT around 5s, although the TTs acceleration after that is pretty awesome
The TT is quite easily tuneable and for a couple of k outlay on top of the purchase price, you can get a car putting out ~390bhp, whereas you'd struggle to get much more than 250bhp out of an N/A (I believe) without some kind of turbo being involved (and more expense). Having said that, an N/A-TT conversion is about 3-4k (I think?), which isn't too bad if you later decide you want more power.
I can vouch for the Supra auto box, which is a dream to drive. Effortless when trundling around and loads of power on tap when you need it.
Go with whichever fits your bill, although with your budget, you'll get a lovely N/A quite readily and would maybe have to wait a bit longer for a really nice TT (although they do come up at that price).