Mark Blake's "Pretend You're In A War: The Who and the Sixties"
But, as the man that brought me here and my buddy Phil Overeem have both pointed out, the Who are the one band I truly love -- my first teenage enthusiasm, which was age-appropriate for a kid growing up in the Long Island wilds in the '70s. And reading made me a Whofan: first an excerpt from Lillian Roxon's Rock Encyclopedia that ran in some Scholastic rag I got at school around the Tommy time, then Nik Cohn in Rock From the Beginning and his NYT pre-release hype for Live At Leeds, then John Mendelssohn and his advocacy for the Who (and the Small Faces, and the Move) in Rolling Stone (when he wasn't hyping his own band).
Mark Blake, a former Q and Mojo scribe who's also written well-regarded books about Pink Floyd and Queen, isn't as compelling a writer as Roxon, Cohn, or Mendelssohn, but he has a journalist's spare style and lots of primary source materal (he interviewed Townshend, Daltrey, Entwistle, and ex-Who manager Chris Stamp, as well as a plethora of participants/eyewitnesses to the saga), and he synthesizes a lot of previously-pubbed material (including Townshend's Who I Am, as well as Blake's acknowledged cornerstone references -- Richard Barnes' Maximum R&B, Dave Marsh's Before I Get Old, Tony Fletcher's Keith Moon bio Dear Boy, and Andy Neill and Matt Kent's beautifully designed doorstop Anyway Anyhow Anywhere).
Best of all, this is the least Townshend-centric account of Who history you'll find, reminding the reader that this was originally Daltrey's band and containing POV from a well-balanced selection of observers. The author also chooses to end his narrative around the time I came in (e.g., with Live At Leeds), but he has his cake and eats it, with an afterword focusing on the Who's impending 50th anniversary tour.
Put this tome together with Richie Unterberger's Won't Get Fooled Again: The Who from Lifehouse to Quadrophenia and you have a pretty complete, well-researched account of the Who when they were still interesting. And you don't need to be reminded of "Eminence Front."