Ya, that's a pretty tough one. You're talking about 3 guys with pretty similarly solid upside. But, I think Brunner has the most. I've watched him pretty close for the 1st 3 games, and he looks like the real deal. You can tell he's still getting used to the rink size and the overall feel of the NHL, but he has a shot at being a difference maker on a fantasy roster.
I would cut Okposo just by default. I actually like him, as well. But, out of Schenn, Brunner, and Okposo in a keeper league he's the odd man out.
Tough call, though. But, I think Brunner is worth a roll of the dice.
20 Team $$ Dynasty League (23 man roster, 17 man minor roster) w/Salary Cap at $75M on Fantrax
G, A, P, +/-, PP, SHP, Hits, Blocks, Wins, Save%, SV, GAA
C - Getzlaf, Pavelski, Eakin, J.Mitchell
LW - Datsyuk, Marchand, Ott, R.Bourque, Higgins
RW - Perry, Little, Franzen, Vrbata
D - Chara, Seabrook, Giordano, Seidenberg, Visnovsky, Gunnarsson, Gryba
G - M.Smith, C.Anderson
Minors - Etem, Mark Stone, Spooner, Pirri, Jankowski, Matthias, Zuccarello, Wiercioch, Leopold, Ceci, Labarbera, Visentin, C.Johnson