I also cross-shopped a tad. I wanted an M3 so bad, and yes I definitely was drawn to the E46 M3. I had an E46 330i that I adored and still to this day regret getting rid of: It wasn't the fastest or best car on the road but it was practical, all-day-driving comfy and with the ZSP and a 5-speed manual it was an absolute riot when I took it out on curvy roads.
Still, for the same reasons as people above I ended up ordering a 135i (still waiting!!!). Basically the more I looked into it the more the maintenance worried me. The E46 is one hell of a car, but it's high-strung and has all the same bad habits as my 330i had (cooling system problems, window regulators etc) and some new ones unique to the more powerful engine. When I did the math I figured that the 135i was 98% of the car with a factory warranty and included maintenance. That became the deciding factor for me; less things to worry about and thus the choice became easy.
It also didn't hurt at all that when I drove the 135i I was reminded a lot of my 330i. The cabin dimensions feel about the same, the dash and all its control feel familiar and the general feel of the car is almost identical. The E46 M3 I drove was a great car to drive hard but the 135i is a better daily driver due to the suspension tuning. I think I'd get tired of the M3's suspension eventually.
YMMV, but I hope this helps
