I think I preferred the Dawnguard stuff. Lots more cool toys to choose from, and their questline had a real sense of urgency. As good as the Volkihar one was I really think the Dawnguard should have had a bigger presence in the main questline, as opposed to just the sidequests.
I made my character a full time werewolf, so unlimited transforms and unlimited time, and revert form all with mods. I didn't even spend any perks in weapons because I just kill them all as a werewolf. So since I like to do that I go with the dawnguard. plus the Troll Companion is the only companion I like to keep around.