Eh, none of them make me hate their guts, but annoyance is a whole another matter. And when it comes to annoyance, there's really no other thing to point at than the obligatory tutorial-spouting character, THE OMO-CHAO.
Nevermind the fact that having to explain mechanics of your game through these forced tutorials implies incompetency when it comes to implementing level design as a tool for learning game mechanics, that thing's only function is to spout stuff you might already know unless you're completely new to the concept of a 3D Sonic game. Many people hate backseating for a reason, it's often insulting to your intelligence.
Hence, the mocking of Omo-Chao by pretty much the entire community, let it be Sonic Seconds or Sega Shorts taking jabs at it or multiple joke hacks implementing him to the game as a punchline like the various Omochao editions. And I'm all for it.