Honestly I have no favorite albums/bands NO ONE ever talks about. If I enjoy music friends haven't heard yet, I talk about it until they've heard it or put it on, and vice versa, so not sure what secret secret unknown bands you're looking for.
I can only guess what YOU might not have heard yet.
well known, but a bit "before your time"
Bonobo (Simon Green)
rather well known, too, but apparently not as much in the US