I would buy an A4... it has alot nicer luxury interior than the others, more room... pretty good pick up. Plus the other 2 are ugly
I think the GTi is just a little bit faster than the A4, but it's a hatchback, and has less room. If you got the A4 2 somethin liter, did the basic mods I-H-E and then put a turbo on that would be pretty damn fast, and nice and luxurious inside. Plus it's an audi