I think Jagr is a very good comparable.
I've seen some other people say this, and I get the reason why (don't get me wrong, it's legitimate) -- but I just think Jagr hit a level of play that is above what Ovechkin ever reached.
I dunno. Jagr won 5 scoring titles in 7 years (and would have won another with NYR if not for a mini-slump in the last three games of the season), sometimes by crazy levels of dominance. During that 7 years, he scored almost 150 more points than Selanne or Sakic (and had the best plus/minus out of the top-eight guys of that period). He continued completely dominating -- in fact, dominating much more -- when Lemieux retired.
I know we can say that Ovechkin's level of goal-scoring dominance for his three-year peak (and maybe for his whole career, up to now) is on the same level as Jagr's scoring dominance those seven or more years, but I really think being a top-goals
and top-assists player simultaneously -- and thus, regular scoring leader contender -- is 'harder' than merely being either/or.
Maybe what it comes down to is that I see Jagr as being the guy who can do it all by himself, whereas I see Ovechkin more as the guy who can do some of it by himself, but to hit his peak level (c. 2007 to 2010) he needs some help. I mean, Jagr scored 127 points at the height of the DPE when the next best guy on his team was Martin Straka.
Anyway, about Ovechkin's "ranking": I also find it difficult to say... yet. I'm gonna wait until he's retired to attempt it, because every year I think "maybe this is the year he'll contend for the Cup / a Gold Medal", and once he does, we'll be forced to re-evaluate him. But every year the Caps choke, or Russia chokes.
He'll certainly way up there in the list of great players and even higher in the list of great goal-scorers. But I don't think he'd be in the top-10 or 15 players. Without giving it too much thought, I'm guessing he's around 20th or something, but, as I said, there's still lots of chance for him to move up.