I have been enjoying the Carolina Wren, though I suspect it will get old pretty fast.
It's not that it's particularly musical or complex: it isn't. But I'm entertained by the delivery -- loud, enthusiastic, almost melodramatic. The little guy sits on my deck, sticks his/her beak in the air, and really belts it out, looking almost like an operatic tenor delivering a favorite piece.
One question for the experts out there: what does this song represent? It's February, so I assume that it has nothing to do with mating. There don't appear to be any threats in the area, so it doesn't seem to be a warning call. Is it territorial? Is s/he announcing good eats to fellow wrens in the area?