What year GTI/A4 are we talking about? I think both cars are great. The A4 would be more flexible because of the extra doors and probably a larger trunk. Although, you can get a four-door GTI also. A4's, base ones, do not come with Quattro (4-wheel-drive). Also, you can get a bigger, optional V6 in the A4 that would make more power than the GTI's 2.0T. In my opinion, the GTI looks better than the current A4 and I see far fewer of them. If I were in your shoes, I would get a GTI. You can get packages that would make the interior just as nice, if not as nice, as the Audi's interior.