Best Britpop band? That’s a question of taste — though if your answer is Oasis, you’re probably wrong, and if your answer is Blur, you’re probably right. From the Stone Roses–tailcoating of their 1991 debut, Leisure, through the electronic decay of their 2003 swan song, Think Tank, Blur defined and then deftly transcended the 1990s subgenre. A quick, albeit obvious, example: from “Girls and Boys” to “Song 2” in a mere three years. Woo hoo, indeed. The massive 21 — named for the number of years since their debut and the number of discs in this box set to end all box sets — is a credible indulgence, collecting all seven studio albums with a plethora of bonuses. Teeming with B-sides, live tracks, and demos, much of it previously unreleased, 21 is both exhaustive and indispensable. You’ve got your early demos as Seymour, you’ve got your legendary, shoulda-been ace sessions with XTC’s Andy Partridge, you’ve got your remixes by Pet Shop Boys, Cornelius, et al. If you can’t rustle up enough change for this bad boy (or the equally drool-worthy vinyl box), each album is available individually with a bonus disc of killer extras. Blur’s heyday may now be a generation away, but this kind of attention to detail makes them, ahem, live forever.