I think the Cavs will win one at home against the Warriors.
LeBron has won a road game in like, 23 straight series. I think that ends in the Finals.
The Warriors are such a good defensive team, and the Cavs have nobody at all to guard Curry (who is a flamethrower right now). LeBron can't cover Curry. The Warriors, on the other hand, can throw Klay, Dray, Barnes, Iggy, and even Livingston at LeBron. They also have Bogut manning the paint.
The only way I see the Finals becoming a close match is if the Warriors suffer an injury to one of their key guys, e.g. if Bogut is significantly hobbled, Barnes or Klay misses games, Dray can't play, etc.