I'll say Ehrhoff. Out of all the rookie defensemen out there, he's by far the least shy about letting off a shot. If preseason is any indication, he's gonna top 225 shots easily, and he may be playing the top PP unit (definitely while Stuart is out).
My (completely speculative) list would look like:
Ehrhoff
John Vandermeer on Philly (if he stays on the team the whole season)
Zidlicky
Bergeron (unless Edm does what they did last year with York on the point alongside Brewer)
Kronwall
Ehrhoff may top 30-35 pts, but I'll guess that that's about it. He seems to me to be the most mature out of the group.
Sorry, I don't see Liles getting very much ice time at all this season around Blake, Foote, Morris, Skoula, McAllister, and Skrastins, let alone PP time.
It seems that Eminger is going to be playing at the Brendan Witt school of defense this season. They don't teach PP quarterbacking skills there, so not too many points from him.
Pitkanen is gonna be really good in a few years. Not this year though. From what I saw in preseason, it looks like he's biding his time learning the league and such. It will pay off big time for Philly in a few years.
Bergeron could be a dark horse in the scoring race, but if Edmonton goes with York and Brewer at the point on the first PP unit, he's not going to be doing all that much scoring. Plus, I have a feeling at some point he's going to get benched because he's uhh... not too good at defense.
Kronwall looked good too, but like Liles, he's also stuck behind a glut of defensemen. I'd expect him to perform similar to how Bykov did last season.
I know nothing about Daley or Kondratiev.
Popovic might be on the list too, but I don't know about his roster status.