I drove a chipped whatever RS4 V8 Avant of a friend of mine last spring(440DIN HP instead of 420)
I still owned my 335i 6mt back then....
Besides the superquality interior, feel, and 100% look, the engine felt torqueless, like my ex 335i was just as fast, only beyond 6000rpm it felt a tiny bit faster..... the steering was quite alright, but nothing to play with like a BMW, only in the snow. LOL
I kept thinking about why the RS4 didn't feel that fast in a way...
Later I was on the Autobahn and a blue Audi tried to follow me from a start towards 150mph, doing his best to keep up and YES he passed me at 130/140mph very slowly:A RS4 V8 saloon. I was still driving my bloody 335i...
At my dealership I testdrove a E90 M3 and besides the shitty interiortrim compared to the RS4 it feels a lot more alive/agile/svelte. The engine is a masterpiece in it's own way. The balance on the throttle, no normal Audi can do that.
If you want a practical fast car:RS4
If you want more or less a driving machine:e90 M3