Who is Superwoman? Friends and Fugitive Death in the Family Bizarrogirl by Sterling Gates & Jamal Igle DC Comics, 2009-2011
I thought the Peter David run (with Gary Frank and later Leonard Kirk) on Supergirl was going to be hard to beat, but Gates & Igle have proven that their stories from #34-59 (most of them collected in these four volumes) have proven to be just as strong.
Not a fan of all the stories, but like the overall tone of the series. Sven the Returned in Vol. 1 and The Shield Maidens in Vol. 3 are some of my favs.
Note: The series is ongoing and will be completed in 2012.