I test drove both a 135i M Sport and M3 (both DCT) before buying. I ultimately bought the M3. If you like stop light to stop light speed, stick with the 135i. It "feels" quicker in that scenario. Chip it and it really comes alive. The torque is no comparison in favor of the 135i. Where the M3 shines is on track, and cornering on back roads. Honestly, given my driving habits, I probably should have went with the 135i. However, there is something to be said about owning an M. It does put a smile on your face. Not to mention it will hold its value much better. There's only so many M's produced. 135's are everywhere.
2007 E90 335i Sedan - Montego Blue Metallic with Black Dakota Leather, Brushed Aluminum Trim, 6 Speed, Sport/Premium/Cold Weather Packages, Comfort Access, Aluminum Pedals, Window Tint
Mods:Active Autowerke Processor, BMS DCI