I think this is in the right place...^^;
So, which of the HMs do you hate the most?
I'd personally go with Whirlpool or Rock Smash. I was annoyed when GSC came out and we got all the new Water HMs because it meant you'd either need to have your water type with an almost pure HM moveset or find another way to deal with it. Thank God they invented the Move Deleter...I wasn't that bothered about Dive in RSE because it was a decent move.
So, Whirlpool for that reason and that it's a generally annoying move. Rock Smash because in battle it's virtually useless. Even when used on something weak against it.
My favourite is Fly. I'm lazy. And it's a decent move. Even against Rock/Ground. You can hide away and hope they use Explosion/Self-Destruct. Though, my luck, they use it after I fly. *headfloor*
I love the other Water HMs too (Surf, Waterfall, Dive).