It's hard to compare these guys as both are very different players, one is an offensive defenseman that will put up lots of points, the other is a defensive defenseman who will shut down the opponent's top lines and play on the PK.
It's like saying who's better between Dan Boyle and Josh Gorges. Both very different players.
A more appropriate poll choice could be, sticking with Oilers prospects, Beaulieu vs. J.Schultz or Beaulieu vs. Marincin.
I don't really know. I voted Beaulieu, but it's mostly wishful thinking. Most of us probably haven't seen a lot of Klefbom. He seems to be coming along nicely. I wouldn't trade Beaulieu for him, as a Habs fan, but it's easy to acknowledge that Klefbom is the less-risky prospect, and may well become the better one. But for now, I'm satisfied with Beaulieu for the Habs.