If you're going for overall band, then you've got a couple of choices...
Two Princes has, from what I recall, the hardest bass chart out of all the LRB songs (does not say much). It also has one of the hardest drum charts and doesn't leave that much breathing space when singing. Guitar doesn't get off that easy either, but not at all blistering.
Fire was the only song that was rated all devils in LRB. Guitar was a bit tricky and drums were lolwut hard. Bass and vocals, however, were not that bad.
Short and Sweet, despite its name, is the longest song from LRB. It's annoyingly difficult for drums and pretty grueling for guitar and bass, but it has relatively little vocals.
Real Wild Child has the only devil-tiered instrument outside of LRB, which is for vocals. It's also got hard drums, but has an easy baseline and okay guitar.
Still, this all kinda iffy since "Cherub Rock" blows all of these out of the water in terms of band difficulty. I guess the LRB section shall be referred to as "rest section"?