Depends what you value in a hockey player. Miller has been consistently great but EP40 is substantial better when both are performing.
I think most people would prefer consistently great (Miller). Personally, I think most fans (at least Canucks fans) vastly underrate how effective Pettersson is away from the puck even when the offense isn't there. The idea that Pettersson quits on his team is nonsense if you ask me. It's a classic case of somebody in his own head. Something akin to MacKinnon prior the hiring his sports therapist. And for that potential alone I take Pettersson every time especially considering, at worst, you'll get an excellent (albeit overpaid) two-way player.