defo 1.8t
ive seen some great tune ups of that engine at awesome in manchester.
i have bora 4 motion at the moment, and a tunned 1.8t would see it off (although not off a standing start cause of the awd!) the one thing to watch is get it tunned well. dont max the remap or go for a cheap remap as your turbo is likly to give up after a while!
find a quality low miles, fsh example of the 1.8t and save 800 quid back for some quality mods, revo remap, diverters and throttle body re alighned full inductiion etc.

i had a remmapped 2.7 bi turbo s4, my fav car so far but was always worried about the turbo's going, would have cost me over 3k to fix

4 motion golf could be a quick option with full system and full induction? but more fun would be had with a tunned 1.8t i recon?
welcome dude, im loving this forum already!