upgrade in price! all the audi dealers like to joke about how people drop a few extra grand for the same car, just for the roundel. it's a good tactic for a close second runner up, but it does hold some water.
everything depends on what you are looking at. if you are comparing A4 3.0 quatro to 330i, 330i will have better performance, but if you are looking at the awds, i think the quatro setup is better than the xi setup. BMWs do have a better rep, almost snobby at some points, but i liked the feel of the bimmers better than the audis.
audi does have a rep for having many issues come up later in life.. but i really dont' knwo for newer gens.