The worst best game is almost certainly a Call of Duty we haven't played. Can't be 100% sure but it seems likely. Not the one where Reagan respects your pronouns even though that's extremely evil because it's funny, but possibly the one where they attributed American war crimes to Russia.

The best worst game, I'm going to pull from Wikipedia's list of games considered the worst and say Sonic 2006 strikes me as number one on that list though Jekyll and Hyde is up there too.