In honesty, I don't see the point of us telling you whether we would pay a one off fee or a subscription to a game that doesn't exist. The final product will dictate exactly what we would do. More importantly, what your customers will do.
You keep saying "we"/"I". I was not asking what you, or anyone else on this forum, would pay for the game or how you, or anyone else on this forum, would want to pay for it. I was asking, in general, what method works best for multiplayer games made by independent game companies. I might not have made that clear enough in the opening post.
Like I said, probably wrong forum for this. As I stated before, what would be best is a good psychology study on this.