Yeah, I must admit K-ON S2 ED2 is quite good - probably because it has nothing to do with K-ON and moe :)
Can't resist to post this: http://www.youtube.com/watch?v=j6zah2KviVo
That link didn't really seem to work. And I agree with the ED being quite good, since it isn't chipmunk or overly moe this time. Still unlikely I'll watch the second season though, too many other anime which I am interested in.
Also, personally, I think I kind of like the Working!! OP. Saw it for the first time while in Japan, and god, it made me hyper.
Which was bad, since it was after midnight and I had to get up less than 5 hours later for school. Oh well. :P