Least favourite opening?

What is your least favourite opening to play against? Mine is the Scandinavian

duras gambit

sicilian

or hippo

goodbye

I HATE the Grunfeld Defense.

I have no least favorite to specifically play "against". If I hate an opening, I hate it from both sides, not just against it.

The Grunfeld? I want nothing to do with it as White, as Black, EVER!

I avoid it as White via 1.d4 Nf6 2.Bg5

I avoid it as Black via 1.d4 Nf6 2.c4 Nc6 (NOT g6) and if 1.c4 move order, 1.c4 g6 2.Nc3 Bg7 and if now 3.d4, then 3...d6 and 4...e5.

Whats wrong with kings pawn?

London system

CocaCola gambit for sure (in my opinion)

"System" openings, it's less the openings and more the chess philosophy of many of those who play them.

Definitely the London. It's just an extremely boring game that almost can't be avoided. I could maybe appreciate it if the players I run into knew their opening. But when I play Qb3 (not a very interesting line but one of the few that come close) they don't respond accurately, they're just playing Nf3 Bf4 e6 c3 on autopilot every game. If you try to do something more interesting, you are probably just giving white a better game. Thankfully, at long last, I've finally found a satisfying way of dealing with it via the Horwitz defense.

Case 1, london impossible. Case 2, king is displaced. Black has a 60% winrate. Case 3... it's not exactly a london.