I have always liked the way the S197 Mustangs look AND sound. My brother had one, an 06 GT.
It sounded amazing with the stock exhaust and drove fine.. AND not one day went by without people smiling. Must've been a people's car..
With that said, if it was my daily driver, I'd probably get the 335i as the bmw is just that much more refined and civilized.
The BMW is sleek, the Mustang is mean.
Get both?
good luck with your choice.
btw - if you understand German..