Here's mine, in order from most liked to least liked.
Match - Pew pew pew. Killing people is fun.
CTF - With special macros to organize tactics, I can get a lot of fun out of this gametype.
Race - It's pretty fun, even though Sonic is OP. Sonic should be given a Doublejump here instead. He still has the fastest runspeed. >.>
Coop - Not that much fun, unless there's a proper level WAD (Mystic Realm) and/or a good custom character (KO.T.E, Hinote, Senku) added.
Tag - Fun if everyone's forced Tails/Sonic. Knuckles is OP here. He should auto-fall after a while.
C.Race - Finishing first to find out that someone collected one more ring than you is just ANNOYING.
HnS - See tag, except this one's boring that once time's up, you literally CAN'T PLAY and just wait there to see if someone finds you. BORING!