I have an e46 m3, and my dad just got a 335i sedan so I will be able to fully test both when I am home this summer

 

First off, great thread topic... With that being said, i'm always in favor of boost. I know some say that there is no replacement for displacement but 2 snails certaily plaster a grin on my face.

335 coupe is my choice, and tuned of course

 

I've owned an 05 M3 and an 08 335i. I liked both cars quite a bit.

The 335i is definitely more isolated from the road. The suspension bushings have quite a bit more give to them and makes cornering at the limit sloppier than the E46 M3. The M3 is much more precise, and handling is much better.

Stock for stock, they're pretty close in performance but the 335i feels faster stock, to me. And, for cheap, you can make a 335i really fast, where E46 M3 mods are much more expensive.

 

I'm actually trying to make this decision right now. While the 335i is the new wave of technology and has cheap power, I'm worried about 2 things. 1. I'd like to see a few more years of fi bmws before I take the plunge. 2. As much as I love bmw's, once I got my hands on an m car, it's hard to go back to a normal one.