In my mind, the best "goal-scoring" season in Bobby Hull's 1965-66. He dominated everyone in the league that year in both goals and points.
His 97 points are 24% more than next highest (Mikita and Rousseau at 78)
His 54 goals are 69% more than the next highest (Frank Mahovlich at 32). There were 6 30-goal scorers that year. Getting 54 in that environment is the most dominant single-season goal scoring in the NHL. In comparison, Ovechkin's 65 goals was in a season of 28 30-goal scorers.
Ovechkin has the highest goal-scoring peak of anyone since Mario Lemieux. His three season peak of 2007-08, 2008-09, and 2009-10 is the best healthy three year stretch of any goal-scorer besides the Big Four (and Espo), and the Hulls. If you look at complete play as a player, it's better than anything Phil Esposito or Brett Hull did. Rocket's peak is in the same category as well.
I don't think he peaked as high as Gretzky, Lemieux, or either Hull as a goal-scorer. But he has put together nearly 15 years of goal-scoring dominance. He easily has my "prime" vote for a goal-scorer.
If I had to rank goal-scorers overall, I would put them in tiers of
1) Bobby Hull
2) Wayne Gretzky, Mario Lemieux, Gordie Howe, Alex Ovechkin
3) Rocket Richard, Brett Hull, Charlie Conacher, Phil Esposito
I don't think Ovechkin>Gretzky is too controversially as a goal-scorer. Gretzky had 3 seasons better than anything Ovechkin did, but Gretzky only really had six truly elite goal-scoring seasons. Ovechkin is something around ten now.
The crown still sits on Bobby Hull's head. Similar length goal-scoring prime, but Hull had the higher peak. If Ovechkin keeps racking up Rockets, I could see the argument. But when you have comparable primes, with differing peaks it's hard to argue against Bobby Hull.