I have a natural love of the pure 68K architecture, but I would suggest it is insanity to even think about anything other than ARM for your 32Bit uc needs... And with boards like the teensy 3.0 it is hard to justify using 8bit devices now!
Actually, and I may have already mentioned this here, I missed out on a chance to buy 70 ARM9 mcus last night for $30.
I'm still kicking myself in the ass over that.
As to 8bit cpus, I just like to 6809 and am almost as fascinated with the 6309 as I am with the 68000. The 6309? Its got 16 and 32 bit capabilities that are surprising for such and old design.
But yeah, ARM is kind of hard to beat. When I recently decided I had to have something tied to my entertainment system, an ARM Cortex A9 quad core appliance seemed like a natural.
After all, for about $100 I have a 2GB system that wouls slap all my legacy hardware silly in comparison.
But we aren't talking practical bloodline, we're talking hobbyist pursuits.
Yes I can get an ARM that will greatly out perform a $4.00 20MHz 68000.
But damn man, I can get 20 MHz 68000 processors for $4 or less now!