User blog comment:Thewikilover/Dawnguard or Vampire? Which side has more benefits?/@comment-5229167-20120714215930/@comment-3524429-20120714235739

Actually, there is a Volkihar quest where you get Dawnguard armor in order to imitate a member. However, you only get the heavily-armored version, IIRC. Besides, you might have better armor or just not like the Dawnguard Armor. Also, not everyone uses X-bows.

Long story short, it's personal preference. If you like vampires, side with them. If you like hunting vampires, join the Dawnguard.