Can't be a single artist (no Mike Krol or Car Seat Headrest!) ........can't be a main guys backing band (no Ike Reilly!) but an actual band.
At various points this title has been a thing of great honor and now well it is almost a joke in this genre but....... I have been - almost daily now - hyping the new release, the 2nd - from Ireland's Fontaines D.C. "A Hero's Death". (Release is July 31st).
So who is the "best Rock band in the world" right now for you? Not a band who did a single great album recently but a band you feel could knock off 5 in 5 years etc. and is at their peak currently. .........and it's "band" not "bands" .......there can only be one winner in the steel cage match of Death.
Rock music is in such a sorry state this doesn't mean nearly as much as it did in the past and a lot of the best choices don't fit the criterion. Radiohead, Arcade Fire, and Arctic Monkeys have all peaked already. St. Vincent would be my answer but she's not a band.
I will go with the Austin punk band A Giant Dog. It's been a few years but they reeled off four very good albums in rapid succession and could easily do it again.