While I learned programming with 6510, I agree that 68000 instruction set was much nicer and easier to read and learn. I would also chose 68000.
This said, 65XX on an early Commodore computers was extremely rewarding to use because there was no memory protection and you could write code altering video memory, mess with sprites, fonts, borders, interrupts, write self modifying code etc etc. 68000 assembly on Amiga was more safe and controlled.
When I was in college, they taught the Computer Architecture course using the 68000. Coded GUI stuff on the Mac 128k with assembler, and it was surprisingly easy, especially compared to doing anything with the 8086.
This said, 65XX on an early Commodore computers was extremely rewarding to use because there was no memory protection and you could write code altering video memory, mess with sprites, fonts, borders, interrupts, write self modifying code etc etc. 68000 assembly on Amiga was more safe and controlled.