Mine is Banjo-Tooie. I love the first one so I keep trying to give Tooie a chance, but I can't get past the level designs. The worlds are huge and there's not enough landmarks/visual distinction in the levels to keep everything straight. Combine how easy it is to get lost with the amount of backtracking the game asks of you and I just end up overwhelmed and frustrated by it. I do think it has a lot of things going for it, but that one problem is just too hard to get over.