Dislike toys, like character: CHEETOR (BM) - Cheetor is by far the best written character in Beast Machines... which isn't hard. But seriously, even on his own merit, Cheetor is well written. His character arc is a natural continuation from Beast Wars and progresses well throughout BM. The original Mega and Supreme Class figures are rubbish. Night Slash Cheetor is nice though.
Dislike character, like toy - HUBCAP (G1). Of course, he's meant to be an unlikeable characters
Both: WHEELIE (G1) - dislike the G1 toy and dislike the G1 cartoon character. However I don't dislike Wheelie in other G1 continuities beyond the cartoon, and I quite like Titans Return Wheelie.
Depends on which G1 Starscream you're talking about, wouldn't it? Sunbow Starscream is pretty much incompetent and useless - nothing more than just a recurring nuisance. But Marvel Starscream was waaaaaaay better where he was an actual credible threat.