Evol is my favorite of the three. While Bad Moon Rising is my favorite Sonic Youth album hands down (my favorite music album hands down, actually!) I really was impressed by the group for doing something completely different as a follow up. Sister is the "Sister" album to Evol, and Daydream Nation is a solidifying of that direction.
I hate voting for "least favorite" things though. Such a silly way to look at great art. Which is worse Guernica or Blue Nude? I prefer to focus on favorites rather than dwelling on what I "don't like as much."