TT Z32 = expensive, hard to work on, probably expensive to get worked on.
NA Z32 = Slow, not the easiest to work on either.

Both are reliable assuming you maintain them and replace the usual wear out items. I think it's mostly a matter of how much time and money you have to throw at it and how bad you want to do 12s.

You might also consider the older z31. Lost of junkyard parts, easier to work on, cheap to buy. I love mine.