I find it interesting that you said mumford & sons...they play off a retro folk rocky tone which is definitely different today but i wouldnt call it a new style.
..muse? i stopped liking them when they said that they took inspiration from dubstep (it was actually a while before that but that made me realize that they will never go back to how they used to be
I don't think I listen to anything new (most of the stuff i listen to is from the 90's) and i dont even think there is anything in the mainstream that could be considered original (i dont even know if it exists anywhere).
Maybe Anamanaguchi...they are really helping to shape the chip tune scene (also ironic because it combines old school video game tunes with relatively generic instrumentals)