Pirelli Cinturato P7 would be a very good tyre for your A4. It offers superior comfort and great traction over wet and dry surfaces.
If you want an economical option then you can go for Goodyear Excellence. You could also look at Continental Conti Sport Contact 5. It lies somewhere between Goodyear Excellence and Pirelli Cinturato P7.
If you are looking at performance oriented tyres then go for Yokohama Advan Sport.