ok mate,
this has been covered a few times - so itd b worth doing a search to hunt down other threads to get more info etc,
buuut my 2cents,
i have an r32 gtst with an rb20engine and box and a rb25turbo - and she goes sweet, slides easy
but if i had more cash i'd probs want an rb25engine and box,
so the bang for buck choice is probs the r33,
with the r33 u get the bigger engine, stronger box, bigger brakes, an anchor and a newer car
just depends what you are into buddy
32>33 imo
edit: heres one of the threads i was talking about buddy, have a read
clicky