Really wanting to pick this up, but I just thought I'd ask if the majority of the players think it's best to play through the MQ before Dawnguard, after, or if it really doesn't matter. I'm thinking I've heard it mentioned that it ties into the MQ in some way?

I'd say before. Im currently playing with one of my oldest chars and she's finished the MQ, but I can't help thinking it how the new stuff would be great early in the game.

before, because of the reason above.

and just, well as difficulty rises the enemies completely change, and it goes in perfect timing/sync with the quests if that makes any sense + after.

My characters currently at level 9, but I think I'll go dl it now . Thanks folks. My character is more of a well I wouldn't say good, but a decent guy right now. Not sure which side I'll choose.

Before I'd say, but it doesn't matter.