I did not read much of that run, but I vaguely recall a first appearance where the Persuader's axe, able to cut through Superboy, atomic bonds, gravity, dimensional barriers, force fields and various 'uncuttable' things, bounced off his face, and he wasn't supposed to be miraculously invulnerable, just 'tough.' I've seen a lot of puffing people up in their first appearance to sell them as the New Big Thing, but I was immediately turned off by this blatant puffery. I'm afraid I never gave him a chance after that.
But Ambush Bug wins for most annoying. Kent Shakespeare, Earth-Man, Superboy Prime, Damian Wayne, etc. are characters I don't like for various reasons or find obnoxious or loathsome, but Ambush Bug is actively annoying to me. Just too desperate in the attempts to be 'funny,' but, to me, not even remotely funny. It's like he's going for that Three Stooges energy, but trying way, way too hard.