Currently, I am doing a mastery build, and it seems to be working pretty good, but I've heard still that a haste build is the way to go, even for 25 mans, anyone care to share their opinion on the matter?
Unless you can get a 5th tick of HR with around 3500ish haste, go for crit. Mastery would still come out better than haste, though. I'd reccomend going up until 777 haste for your 5th tick of HR during Divine Favor, then change your stat priorities to Spirit>Crit>Mastery>Haste.