This is a tricky one. With 3 forwards already picked, I'd cross out Skinner and Iginla pretty quickly. I'd worry about Byfuglien ever reaching the numbers he did last season again, since the vast majority of them came in the first 3 months of the season. Yandle and Green will likely be amongst the highest scoring defencemen in the league for the next decade. Green has better team-mates of course, but he's also a little more unpredictable considering his injury concerns and the fact that Washington will likely never allow him to play the rover-type role he used to. Yandle is probably the safer bet here, with Green having a slightly higher ceiling.
Bryzgalov is also an interesting option of course though, particularity if you plan on competing for a championship in the next few years and if goalie stats play a large role in your league. Most of the other top goalies in the league will likely be picked as keepers by other teams, meaning it will be slim pickings in the goalie market come draft time.