I was in a similar position about 2 months ago before I bought my valver mate.
Ive got to say there are both really nice cars, the GTI looks and is slightly newer, is it 120bhp and the 0-60 is quite impressive as I believe. though top end wont be as good, however how often are u up there! They are more expensive to buy and more expensive to insure. And they look a bit more smoother and subtle.
But the valver is a lot more agressive, when I owned my old car and martin came flying up behind me I certianly moved out of the way as fast as possible! Plus with its massive bonnet buldge and flared arches its looks well mean! Anyway its cheaper to buy and on insurance, plus for the money u are thinking of spending on a GTI you can get the best example of a valver and still have change, to put towards your cheaper insurance! The engine size is bigger, more bhp as standard and possibly more options available for tuning as slightly bigger engine, where as the 1.6 is doing well at an impressive 120 bhp! Bad points, older car, but that can mean less people have them, u wont see as many on the roads as GTIs. Might have more problems with as older but for the money u should be buying a minter! And tell you the truth not much else I can think of as Im feeling tired!
But end of the day its what u prefer mate, you will already have a choice in your head and no mater what u will end up going for it!
So which do you prefer?