Personally, I've usually considered the Spectrum and Atari 8-bit to be the superior machines. But this isn't due to raw tech, because frankly, the C64 wins on that score. The C64's biggest weakness was that it required almost godlike programming skills to bring out the full capability of the hardware, and worse, not even a reasonable subset of those abilities could be accessed from BASIC without POKEs that were easier to implement in ASM. Seriously, C64 BASIC was hideous. The only thing that allowed Commodore to get away with that pathetic excuse for a bundled BASIC was in the states the C64 with a disk drive was so cheap that mommy and daddy would buy junior a C64, 1541, and a couple of games, and most wouldn't even bother to learn programming.
Here's a comparison from the time period.......
Person A: Got a brand new C64 and 1541 for christmas.
Person B(Okay, okay, this guys is actually me): Got a brand new Atari 1200XL and a 1010 for christmas. (Trust me, 1050s were EXPENSIVE when they came out)
Fast forward a year........
Person A: Wants a bunch of new games
Person B: Wants Action! (I asked for Action!, I got a 1050 and MAC/65, I could deal with it.)
The reason is, AtariBASIC for all of its faults, actually made learning to program something fun and rewarding. Talking to friends who had C64s who wanted to program they had nothing but ill to say about the built-in BASIC, I wound up being their go-to guy when they wound up ditching the internal BASIC for ASM as well.
It's kind of funny, but it took until the 90s for a series of games to come out that got me excited, MechWarrior.