My favorite old-timers are the usual suspects: Bangs, Meltzer, Shaw. I'm sure I'm in the minority but I think Christgau's writing in the '70s was often very insightful. I thought the writing in Bananafish was outstanding, esp. Seymour Glass, Roland Woodbe, and Earl Kuck (whoever that was). Mark Dancey's Motorbooty was a great satire zine. Black to Comm and Superdope were great reads. I loved Byron's writing when I was a little younger but I don't find him dependable -- guy's too entrenched (and Thurston is a jackass).
The Wire's Keith Moline is pretty good, and Marc Masters is a good, no-bullshit guy as well. Dude who does Yellowgreenred is an excellent writer (he posts here, as you probably know), though he likes some stuff that I can't stand (that's fine, he's not stupid about it). Bill Meyers at Dusted writes intelligently and lucidly about experimental music, one of very few people doing so right now. Dan Warburton at Paris Transatlantic is probably the single best writer on experimental and "difficult" music. My friend Brian Olewnick, a Paris Trans contributor, writes a good blog about experimental and improvised music. Mark Prindle, also a friend, is one of the funniest, smartest writers of my generation and I read his work religiously. And I'm not gonna lie, Mosurak's column is a great resource and I always read him even if I don't always agree with him or particuarly love his writing -- Still Single's important 'cos they review every underground rock record that matters and the column's reached a point where people send him every record that comes out and he doesn't hafta kiss anyone's ass.
And I sincerely respect and admire my colleagues here on Termbo and at Z-Gun, two organizations of which I'm proud to be a part.
DeRogatis is a moe-ron, Klosterman's a jagoff who shoulda stopped writing about a decade ago. I liked Chuck Eddy's heavy metal book (which isn't actually about heavy metal, unless Morrissey and the Swans also count as metal), but I find his columns undigestible.