Good evening,
I voted for both, as I have both, and my platform of choice for multiplatform games depends on which one offers the highest quality version of the game. In the event of a draw, it will then depend on the multiplayer aspect, notably the community (I have lots of friends who use PCs, but for playing with people I don't know, I find that the xbox works better.). Should there be no multiplayer component to the game, price and/or my mood at the moment of the purchase will determine which version I will buy.
The E3 preview of Divinity 2 from Kotaku makes me believe the PC version will be superior, so that should be the version I will get. But things can change. In my experience as a QA tester, I have seen miracles happen to games when they get very close to their planned release date.
With that all said, I am very excited about this game and can't wait to get my hands on it

Cheers,
Rythok
P.S.
Kotaku Divinity 2 preview