I've got a Corrado VR6 in addition to my
Ibiza so I've got plenty of experience with both engines. My advice based on the assumption that it won't be used as a trackday car is :
If you want much more than 200bhp, get the 1.8T. Getting a VR6 to 250bhp+ will cost you £2K onwards using a supercharger and it's not plug 'n' play - the owner of the best supercharged Corrado VR6 is a mate, I've driven it plenty & know all the pitfalls. You can get the same, more consistent, power from a remapped K0-4 1.8T with better low-mid range torque. If you want to go over 300bhp, both will cost about the same to do properly but the VR6 won't need internals, other than a CR drop, until about 350bhp+. For your apparent purposes, get the VR6 with the intention of leaving it N/A, fit & forget. If you want to mess about with it , you'll get better bang-per-buck from the 1.8T.
If you go for a VR6, try & get a 24v 2.8 from a V6 4-Motion if possible and use an 02A gearbox for FWD. If a 12v is all you can manage, try to get a '95-on 2.8 with OBD2 management. Don't waste your time with the 2.9 Corrado ABV engine - the extra 69cc isn't worth it and the late 2.8 are just as powerful with much better management. If you get the 12v VR6, while it's out of the car, drop the gearbox off and replace the timing chain tensioners and
guide rails - the parts aren't that much but the labour stacks up if done later when in the car.
In all cases use the stock ECU, aftermarket management will just add unnecessary cost.
factor 
