Individually, LW might be his best position. A player has to play where the team needs him most though and that is C(A)M in Barcelona. However, I'm confident he'll do great things in both positions. Somehow you can compare him to the Don in this regard. I will never forget the Clásico when Don Andres fucked Real playing as LW.
Was it the first Classico after Ronaldinho left? I remember him playing in LW during that period and he quickly made us feel that Ronaldinhos gap is well treated