Edler for me..

Let's not forget that Edler is only 26 years old... and he's a big guy.
Big guys take just a little longer to hit their full-stride in the NHL (see Chara, Zdeno).
I love that VAN PP... the Sedins are just so magic. It's good stuff.
Edler has 22 PPP there last year, but I think the potential for 30 PPP is there (and 50pts).
And Edler has a cannon of a shot that he unloaded for 228 SOG last year - so he's used for two options on that VAN PP, pass & shoot.

Shattenkirk is a solid player, who had 43pts and 18 PPP last year.
TBH, I'm really not sold that the forwards on STL are a group that can push him into that 25 PPP area. Also, he's option #2 on that STL PP. Point shots are going to come from AP (mostly), which is a 50% chance of being a pass from Shattenkirk... but for that reason, Shatty will consistently fall 5-7pts below AP's point totals. I realize he is young (23 years old), but he's a smaller player and those guys usually just excel in the NHL at a younger age. Where am I going... I'm saying that 43pts may be Shattenkirk's NHL mark... that's where I see him for the long-haul. And a lot hinges on AP, who was great with 51pts and 24 PPP. If Shatty does manage to hit 50pts, it will be because AP got up to 55-57pts. Is that probable? I say no.

In summary, I think Shattenkirk & AP are there... and I don't think they'll necessarily increase any more (just because they are young).

I'd hold the 26-year old Edler, mostly based on a more cohesive PP-unit in VAN.