I bought the 128i:
1 - because my wife said I can't have another car with as much HP as my modded Subi did.
2 - the insurance was cheaper
3 - the reliability factor. I have read alot of posts on here and the complaints that I read are 95% about something going wrong with their 135i.
I do live in Germany right now and drive from PHV Heidelberg to Mannheim every day for work. Two stretchs of road i can really get on it, and find myself doing it more then I should be. Other then the ability of the 135I to get there quicker, 155mph is pretty dang fast in my 128i and it gets there pretty quick on its own. To be honest the only car to have passed me at those speeds is an SL500. Not that I think I can race for top speed against anyone, I just go that fast because I can do it legally and its a rush!
If money wasn't the concern and my wife didn't care i would probably have gone with this AC Schnitzer tuned 135i that used to be in K-town. $46k for it though. But from what I was reading it had a LOT of packages and an upgraded exhaust and turbo from AC with well over 300hp and torque. Also no speed limiter either. The body kit was sharp too. All factory warranty as well.
So to sum it up....other then occasionally missing the blinding ripping power of my old subie, i've been happy with my purchase. I look forward to the drift school my wife got me for my birthday in Sept!