I'm going off the board here for Jason Robertson. He holds the single-season team record for production by 16 points.
If you're going by any more than a season or two, that's prime, not peak.
As much as I like Robertson, i don't think there's much argument for Robertson over peak Benn.
As much as we rag on Benn's weak competition, an Art Ross is still an Art Ross. Not counting massive games played differential, Has there ever been a 6th place point finish more impressive than an Art Ross winner from a purely offensive standpoint? Im willing to bet it's a very small number if so and I doubt Robertson is on that list. Benn still has a larger production gap over his comp than Robertson did last year.
And one more thing that tends to be overlooked is that Benn still finished 2nd in points, 3rd in goals and was a hart finalist the next year against slightly better competition. His peak was sustained where there isn't much question as to whether he's a 1 hit wonder Unlike Robertson, who only really has last season in terms of elite production.
And that's just talking offense.. Benn brought a physical element to the game Robertson lacks.