I've been playing a DK since Wrath pretty faithfully but over time the changes to the spec have been driving me more and more away from the class. I don't really like the newer iteration of DK all that much, especially for Blood which I find has a very slow play-style that relies on the artifact too much right now.
While Vengeance isn't perfect, compared to the other tank specs it feels much more active and visceral with its animations and gameplay, with the artifact really just adding more utility and interesting procs (like dipping into meta form when eating souls), especially when compared to Prot Paladin, Bear, and Brewmaster