Sorry Nec and Polo - disagree with you. Although I haven't played the CPC, I have both C64 and Speccy.
Back in the day, a good mate of mine owned a C64. He thought it was a gift from God, able to trounce all-comers from all other systems at everything in every way every time. That is, until he played BJ. Granted, the Speccy is sprite
-graphically inferior (to the original. But, then again, so is the C64!) and lacks sound; but gameplay is excellent. The first level alone was sufficient for my mate to prefer the Speccy despite these shortcoming; so much so that he never played the C64 again.
The C64 has clearly not been playtested - it's gameplay is buGgered. Enemies drop onto the top-left platform, as they should. BJ should be able to fly over and above these enemies - in the original he can, and in the Speccy he can; but he CAN'T on the C64. Why? Fat sprites. So fat, in fact, that their size horribly hinders gameplay at all times ruining any fun it may have had. Gameplay is therefore buGgered. And fat sprites are graphically worse than the mono-but-accurate sprites of the Speccy.
So: C64 is for fanboys.
Speccy (and perhaps CPC) is for everyone one who enjoys the more authentic look and proper gameplay. Of the three main systems, CPC and Speccy are not that dissimilar, with the C64 lagging way, way, way behind. Had it been play-tested and corrected... who knows.