Where I'm at right now...
Gretzky vs Orr...I've seen enough evidence presented to suspect that Orr was probably slightly more valuable on a per-game basis at his peak in the early 1970s. If you expand this to include the entire prime period of both players (and basically we can boil this down to Orr's career compared to Gretzky's Oilers career) I'm less certain that any advantage still exists for Orr. If it's a dead heat, I think playoffs tips the scale to Gretzky. Two extra Cup wins and a little more substance outside of those wins as well. Not a lot, but when it's this close you have to consider every detail. So all things considered, I think Orr vs Oilers Gretzky could reasonably be classed as too close to call. That leaves Kings Gretzky as the final tipping point. While I don't think it adds a lot to his case, it certainly adds something. It's enough for me to feel comfortable ranking Gretzky over Orr as it stands at this moment.
Gretzky vs Howe...I do believe Oilers Gretzky reached a higher level of performance that peak Howe. Gordie certainly had the more well-rounded game, but he needs those points in his favour just to make it close. Gretzky was so overwhelmingly good offensively in the 80's that he was able to out-score the deficiencies in other areas of his game. There were a couple moments when he didn't (1982, 1986), but Howe has a couple playoffs in the 50's that I think he'd take a do-over on as well. What makes this a close call for me is just how good Howe was in the 60's, both regular season and playoffs. While I don't feel Gretzky's post-Edmonton career really adds that much to his legacy, Howe's post-peak career adds a ton. After age 30, I don't think there's any question that you'd rather have Howe than Gretzky. Is that enough to push Howe above Gretzky? It has me thinking, for sure. Gretzky still has great moments later in his career, just not Howe's sustained uninterupted excellence. The 1993 playoffs, and the ability to lead the NHL in assists as late as 1997 and 1998 in a completely different environment than he played in a decade previous are late career highlights. I'm leaning Gretzky, but still undecided.
Howe vs Orr...I'm sold that Orr's per game impact was greater than Howe's. But if Gretzky is bringing a knife to a gun fight in a longevity argument against Howe, Orr is unfortunately bringing a white flag. It's just too hard for me to overlook what Howe did for 15 years longer, even if I give advantage to Orr for a seven year window. Howe giving an otherwise average roster multiple chances at the Stanley Cup throughout the 60's is what gives credence to the longevity argument. It's one thing to speculate about a player being great for a long time giving you more chances at winning more Stanley Cups, but we don't have to speculate with Howe. He absolutely kept Detroit relevant and competitive in an ultra-competitive decade that featured rosters full of all-time greats in Montreal, Toronto, and Chicago.
Lemieux vs the field...I can't see any reasonable argument that places him above Gretzky. You could maybe try to argue he was marginally better offensively in some isolated spurts. But the inconsistency in terms of availability makes this moot in a hurry, before even addressing the defensive cost of his offense, which appears to be greater than Gretzky's, backed by both the numbers and the recollections of observers.
A Lemieux over Howe argument is more conceivable, if for no reason other than they played decades apart so there is at least a seed of doubt. But I believe it is nonetheless flimsy. About the only thing Lemieux really has in his favour is offensive peak, and the gap there isn't as great as the numbers would initially make it look. There's been a lot of discussion on this over the years. Some of the research would have you thinking that Howe's early 50's peak was in fact at a Lemieux-level offensively. Other research presents a pretty good case that the early 50's was a bit of a perfect storm in terms of Howe being positioned to bury the competition in scoring. It has all been good discussion. However, I feel that even if Lemieux is accredited with the maximum peak offensive advantage over Howe that can reasonably be argued, it is still not enough to bridge the gap everywhere else. Unfortunately we don't have the plus/minus data from the 50's available. But absolutely every contemporary account agrees that Howe was a strong 200-foot player. His imposing physical presence is raved about. There's enough circumstantial evidence that I can comfortably conclude that if Lemieux's peak years were better than Howe's, the gap is no larger than the gap between Orr and Howe's peak years. And as I wrote above, all those extra great seasons Howe produced pushes him past Orr for me. Naturally it must also push him past Lemieux.
Lemieux vs Orr is a different animal, as both had short careers in terms of games played. Lemieux lasted much longer, but also missed enormous chunks of games, even full seasons, in his prime. Orr had a short career, but scores much higher on the reliability chart. He didn't miss that many games between 1969-1976. Lemeiux's list of missed games/seasons needs no detailed recounting. Given the all-around greatness and 200-foot impact of Orr, I don't see any good argument that would have Lemieux better on a per-game basis, peak or prime. And while it may seem illogical to give a longevity advantage to a player who was essentially done at 26 versus one who played games at age 40, I'm giving it to Orr for the reliability reasons outlined above.
Still open to more arguments until the voting is closed.
I don't care that he contributed nothing of consequence after 1976"). To try to claim that he's a more dominant playoff performer on account of the fact that his TEAM did things like post a sporty 8-0 playoff record against the hapless, combined 19-games-under-500 Blues teams in their Cup runs is NOT a particularly legitimate one. 
