A comparison I typed up 7 years ago that seems to have helped a few people choose between Dawnguard vs Volkihar.

Dawnguard gets:

  • Pet huskies
  • Pet armoured trolls
  • Master Level trainers in Archery, Heavy Armor, Restoration, and Smithing.
  • A couple followers
  • Better crossbows
  • Easier access to Dwarven and Elemental bolts
  • Easier access to the spells Stendarr’s Aura and Vampire’s Bane
  • Chance to convince Serana to cure her vampirism.
  • Attacked by Volkihar Vampires. (I think) Guards/Citizens will get involved with the fight, risking their own lives to help.

Volkihar gets:

  • Pet death hounds
  • Master Two-Handed trainer and Expert speech trainer
  • Thralls in the castle you can feed on
  • The Ring of the Erudite, Ring of The Beast, Amulet of The Gargoyle, and Amulet of Bats
  • The Bloodstone Chalice, to enhance your vampiric powers
  • A free player home with merchants (the castle itself)
  • The chance to turn your spouse into a vampire
  • Easier access to Necromantic Healing and Heal Undead
  • Attacked by the Danguard in the wild. Guards/citizens won’t help with the fight.

Both sides get:

  • Serana as a follower
  • Auriel’s Bow and Bloodcursed arrows
  • Access to Vampire Lord form and Bloodcursed Arrows*
  • Durnehviir
  • Radiant quests to kill vampires**
  • As long as Serana is still a vampire ** Yes, Members of Clan Volkihar will request that you go kill vampires. Don’t think the Dawnguard are the only ones upset at random vampires attacking towns!