When "Banshee" was the song of the day, I believe my comparison was of letlive. to a bastard child of Refused and Glassjaw. While I stand by that simile, I would throw a bunch of other bands into the mix if I were trying to define letlive's sound. They're a post-hardcore band in the truest sense of the word, building on the hardcore genre in a myriad of ways.
Case in point: today's song, "The Priest and Used Cars", which has a punky energy that brings to mind Protest the Hero and another helping of vocalist Jason Aalon Butler's virtuosity, which is often reminiscent of Claudio from Coheed and Cambria (if Claudio had a more frantic, manic energy). It's a tasty combination.
But I could go on all night about who letlive. sounds like at one moment or the next. Why not listen to "The Priest and Used Cars" and see how awesome they are for yourself?