Slow, simple, boring. These three things make for a good daily driver. Granted, we all have different definitions of these three things, so...
Only thing I can say about Audis is that comparatively speaking, parts will be more expensive than something more common such as the Accord/Camry, Civic/Corolla, etc. One of my guys has an Audi 90 20v, he picked it up on the cheap, but it'll end up costing him in the long run I think.