Well I had C128, and Amiga 500 & 1200... As a coder and composer, I can guarantee, I'm much more creative with hardware limitations.
And if I look at the platforms: C64 was a bit to restricted, and A500 had far to much to offer. I enjoyed using exploits on C64 to achieve the unimaginable (here are a few tricks I'm talking about: http://en.wikipedia.org/wiki/Commodore_64_demos). But Amiga had much more processing power, everything could be done with planar graphics - where's the fun in that?
Not to mention the SID, love the sound of it - and sampled music just can't replace the analogue synths.
You've mentioned C128
But you're right, C65 was discontinued because of the Amiga - it was cheaper and faster...
Ps: I mentioned the C65 because, if Commodore is really making the C64 (x86) PC, they should rather finish the C65 project.
Science and religion are in full accord but science and faith are in complete discord.