I have done research on this topic H&R is by far the best

 

Hi Nevalite;
If this is primarliy a street car I would suggest Eibach springs.
As a service and performance shop I have installed and driven all 3. I would also suggest new shocks (Bilstein sport or heavy duty), while you have the car apart unless you already have fresh ones that will accomadate the lowered ride height. Don't forget new bump stops either.
The Eibach's have a progressive wined that will give good ride but as soon as you start to compress the suspension in cornering they tighten up allot. I have found what I have mentioned above to be a great street setup.
If the car however is used mostly for the track the H & R would be a good choice.
Also, if you haven't though about sway bars they do wonders. A stock Audi tends to under-steer. So when selecting sway bars look for a set-up that will be able to hold the rear of the car very flat. This will induce some over-steer which will help counter the car's tendency of pushing so much. However over-steer can be trickier to deal with until you get used to it.
Good luck!
Tom

 

My brother, and I have b5's with H&R race except he has bilstien shock while im on non-sport shocks. My GF also has H&R race on her car. i love the ride and the drop although on big dips on the freeway i do bounce a little bit but not too much thanks to the progressive spring rate. It works good with the stock shocks but would be even better with upgraded shocks. Go with H&R