Have you had German lagers in Germany?
I have, actually, and it's kind of what convinced me "OK, that's it, I guess I just hate lagers". These were in Switzerland actually, but were German beers from not too far over the border.
I recall liking Urquell a lot. I don't recall butteriness or diacetyl. Interesting. I more remember liking the hoppiness and the hops, and the relative lack of the mystery flavor which I dislike.
I haven't had them in a while, but I recall liking Becks and Heineken. And tend to dislike Saisons, they are ales of course but share something with the lagers I dislike.
I guess after all that I'm just hoping for a lager yeast or two that work for me. The yeasts least likely to give the flavors I wish I could better describe.