Sonic The Hedgehog - Spring Yard Zone
This zone is probably the most boring zone in the game. It just doesn't appeal to me at all.
Sonic 2 The Hedgehog - Wing Fortress Zone
This zone was difficult and tedious to play through. I really hated the platforms on side of the plane that opened and closed. Too many bottomless pits.
Sonic 3 & Knuckles - Sandopolis Zone
This zone overstays its welcome. If it wasn't so long, I wouldn't mind it. The boss on act 1 is horrible; you just let it commit suicide. The boss on act 2 is pretty neat, Eggman hiding inside the statue thing. The ghosts are annoying.
Sonic Heros - BINGO Highway Boss (Robot Carnival)
This was an extremely boring boss fight. All you did was attack badniks over and over.
Sonic Adventure - Big's Stages
Fishing? Really? It was boring and made no sense. This is the most boring gameplay ever.
Sonic Adventure 2 - Knuckles & Rogue's Stages
I didn't mind them as much in Sonic Adventure (mainly because all three of the radars worked at once) but they're extremely boring and tedious in SA2.
Sonic Rush - All
This was a game I just couldn't really get into. I think the fact it was a DS game didn't help it much. I didn't like the split screen effects AT ALL. It also seemed to attempt to combine elements in both the 2D and 3D Sonic Games, and this really didn't work for me.
Sonic The Hedgehog 2006 - Crisis City
I just don't like it. I don't like its return in Generations either.
Sonic Generations - Cris City & BOSS Time Eater
I've always hated crisis city. - All the characters talking to sonic during the Time Eater Boss Stage really annoyed me.