dont want to spend much more money than the s3 and i cant find any thing better
That might not help you in your search! I'm surprised you didn't like the Z4M, Ive driven a few 3.0si models and loved them so I can only imagine the Z4m is just better.
Just go for the RS4, I did after my S3, and you'll soon forget about the S3, and realise what a bland drive it is(no offence but you'll know what I mean). everything you do in the RS4 is such an occasion
Other than that, what about an E92 M3, Ive not driven one, but they look and sound awesome and get rave reviews.
Lexus ISF??
Passat R36??
Porsche 911 Carrera S.
they would all be on my shortlist.
Good luck in your search and enjoy the test drives