Well, Clarkson is a GTI fan and it's raining so I'll put my neck on the line and guess that Clarkson will say the GTI is a better all rounder!!
My brother in law owns an M135i and says it's awful in the wet! I reckon if it is a PP car with the better diff, the GTI would be in with a shout.
Either way, lets face it.. They're both excellent cars.