Do what feels right for you/your character and you won't go wrong.
Incidentally, if you're ever considering playing a character who gets 'corrupted' and turns evil, that seems like a good way. = D --- Remember: IamI3rian told ya. Funner is NOT a word if you're older than seven.
Well... the Dawnguard is the "righteous" side, so it'd make more sense for you to join them., They're for protecting the population and all that jazz.
The Vampires, however, kinda wanna take over the world and lots of their missions involve killing innocents and the like.
I'd personally go Dawnguard, but you can always perceive events differently in your mind. For instance, you want to protect Serana from the Dawnguard so you join the vampires with the intent to stop them from the inside. --- ~If you sprinkle when you tinkle~ ~Be a sweetie and wipe the seaty~
However... isn't a decent helping of a shade of gray a good thing?
Too many quests in Skyrim are cut and dry. Having more than Saadia (which isn't even gray... just a matter of opinion who's right) and the civil war (which is easily argued that both sides are equally right/wrong) is a good thing no?
That said, again I'm not certain. I haven't played through them yet... though I'm almost certain siding with the vampires is not a 'good guy' option really. --- Remember: IamI3rian told ya. Funner is NOT a word if you're older than seven.
Let's see Vamps trying to blot out the sun, and take over?
Or people killing said vamps trying to blot out the sun and take over?
That said yeah they are a bit black and white about it but that's okay. Any ways while they're a bit hostile towards Serana they grow to deal with her if not really accept her. --- Currently playing: Skyrim (PS3) Mass Effect 2 (Ps3 5th Run) Minecraft (PC) Currently waiting for: Naruto Ultimate Ninja Storm 3, GTAV, LR:FFXIII