I listened to a bit of Alt-J, downloading the album you mentioned BUT I have been unable to create a CD for my car, since my computer is falling all to pieces. I do a lot of driving and that's when I can seriously LISTEN to tunes. The 2 songs that stood out were the ones you mentioned - the Tessellate video was awesome, and deep - but the others I looked up were dull. I haven't disregarded Alt-J, but I'm only being honest when I admit to being less than obsessed. If there was something about this band that grabbed my attention, I would have listened to more of it by now.
Now, you have built up a resistance to Skrillex that I've heard just about enough of, young lady. Skrillex is unique in that he is ever evolving and changing up what he is doing - since he worked with Korn, Korn seems lacking without him. He won a Grammy! Did you watch the video? It tells a story of a neighborhood being evicted, while the Indian home called on the powers of nature and the little black and white children looked on in awe, being taught how to stand their ground. It's like an awesome mini-movie with kewl background music - when the Skrillex kicks is, it is coordinated with important aspects of the story you should pay attention to. Plus, this song is totally reggae (Damian Marley!). This is a Quality Video - meant to influence the youth of our nation. Watch it again:
and this one too - do you like Rammstein?