definately, definately the R33 GTR. Push the thought of r33 gtst's being riced up with gtr badges way out of your mind and buy the GTR.
IF you do end up buying the R34, they look hot as hell with some big wheels and dewinged.
Either car you buy your onto a winner.. but I recommend buying the GTR first.. I believe it will depreciate a lot slower than the GTT will. As much as r34 gtt owners on this site dont want to agree with me, I believe they will be dipping into the high $20k bracket within the next few years.. I think GTRs will strongly hold their value for years to come because they are a highly regarded enthusiasts machine.
PS. for everyone saying "Go something different, get a GTT..." I've seen more R34 GTT's driving around my area of brisbane than I have seen actual, genuine, real rb26dett equipped r33 gtrs driving around.