http://www.uesp.net/wiki/Oblivion:Attributes that gain a bonus:
Lore Differences:
Cyrodiilic Vampires were considered the top clan in Cyrodiil because they ousted all other competitors. They had eradictated all vampiric rivals within their borders. They are possibly the oldest clan in Cyrodiil due to their name being lost in history. They also are the most organized, considering they abide by strict tenets(which some of their members are too ignorant to follow). All other provinces had more than a single vampire clan. The others could have a single tribe, but it is not known. The Whet Fang could be the only vampire clan in Argonia as well. They worship and follow Molag Bal and Clavicus Vile.
Volkihar are only known for reaching through the ice without breaking it and freezing the blood in people's veins. In Dawnguard, all I can say is that they turn into large bat-like creatures. Volkihar possibly follow Molag Bal.
Personally, as obvious, I prefer the Cyrodiilic vampires. The gameplay bonuses surpass the ones in Skyrim and when starved for 72 hours, I think a Cyrodiilic vampire has a chance to best a regular vampire in Skyrim.