Hi matey, I've got the 170 tsi and had the 140 in the past too.
Unfortunately never driven a 2.0tsi though, so can only give you my side!
I think it comes down to how much you drive and what economy you would accept? Along with how much you enjoy driving. If fuel is no concern (you mentioned an r32!) then I'd strongly sway towards the 2.0TSI as its a less complex higher output engine to begin, plus being a GTI has a couple of nice features over the gt.
I went for the tsi because its a nice mix of power and economy, I got upto 50mpg on a motorway run with the 140ps remapped. It was also producing 197bhp (they can be mapped upto 210ish depending on rollers). The extra power makes all the difference, transformed the car.
I didn't get a diesel because of the dpf and I think I'll wait until I can afford a CR for refined diesel driving! But if you like the pd units they are pretty amazing, good mpg and stupid amounts of torque!
If you want to save some money find a 140/170 tsi (same engine different software) to the spec you want it with the money saved. The 1.4 tsi is easily fast enough for every day driving with a remap.
I've averaged over 4000 miles 36mpg with it being a mix of motorway and short commutes. On my last tank mostly motorway doing 85-90 I got 39mpg over the tank (calculated).
With regards to upgrades, realistically a turbo back exhaust, intake, bigger intercooler, and a remap. You'd be looking at 250 absolute max with these. You could go further and get a hybrid/k04 turbo but not huge increases, maybe 280bhp (I don't know the limits of the internals).
With the GTI you can read about it on here and get an easy 330bhp with a k04 (and other bits but best to search).
All comes down to how much power you want and what your budget is.
Personally I'll be buying a diesel next time when hopefully the CR unit has come down. But if I was buying now I'd still buy the 1.4 tsi and remap it (like Im going to!) And enjoy 200ish bhp and economy benefits!
Any particular questions about the 1.4 tsi let me know :)