i have had 2 r33s, one slowish(stock) and my one now which has more power.. i have a friend with an s15 and also a friend with a r33gtr, and have driven both on the street, and have driven my car and the s15 at a skidpan day in wet/dry conditions..
simple answer for me would be get the gtr if you have the money to keep it, because maintenance is a lot more expensive than for an s15/r33
although the gtr feels larger, the handling is neutral with lots of traction, and they are very quick with minimal mods just like an s15..
you need more modification for a gtst to keep up with a gtr or an s15, definetly the slowest out of the three mod for mod or even stock.
in terms of handling between the s15 and r33, they are both a bit taily with some extra power, but the r33 definetly feels front heavy, and it is easier to push into understeer, where the s15 feels more balanced between front and rear..
s15 interior is also the tackiest, (but obviously newer looking!)