Let me try and break down my argument to make it clearer:
Both Gretzky and Orr played in eras marred by expansion (Orr particularly)
Gretzky played his career on a better team, with better depth of talent, and with better coaching and management. I think this should be inarguable (Tom Johnson is not in the same league as Glen Sather, and I never did care for Sather).
Orr played his career with debilitating knee problems that cut into how much he could train, and cut into what he could do (or attempt to do) on the ice
The coaching Orr received was rudimentary compared to the coaching Gretzky received; this was the case all the way through their formative years of play.
I have already made it clear that Orr, when on the ice, impacted the success of his team more so than did Gretzky (when Gretzky was on the ice). I am prepared to concede that Orr benefited significantly from expansion, but Gretzky also played in a relatively weak Smythe Division in his glory years (Los Angeles and Vancouver were usually horrible, Winnipeg was below .500 more often than not, and in 81-82, an 18-49-13 Colorado team with a GF/GA of -121 [worst in the league] was in the Smythe with Gretzky's Oilers). And the Campbell Conference, as a whole, was not as strong as the Wales Conference. Playing the sad-sack Kings and Canucks a bunch of times each year, as opposed to playing the Islanders a bunch of times each year, surely didn't hurt.
If the Oilers outscored their opponents by around 40 percent when the Wayner was on the ice during his Oiler years, versus Boston outscoring its opponents by nearly 2:1 when Orr was on the ice during his Boston years, then that kind of massive discrepancy should suggest that Orr was a more dominant performer (if only by a narrow margin) than Gretzky when we control for expansion.
Gretzky was a more cunning and sophisticated individual with the media, and Bill Tuele did a great job of keeping people away when Wayne wanted them to stay away. Orr was poor with the media, untutored about how to use it to his advantage, and never understood the power of his own brand (Gretzky ALWAYS understood the power of his own brand, and cosmetic appearance). One guy would go to youth hospitals quietly and demand that it be kept quiet; the other guy would go, but make sure his trips leaked into the media. Orr was never going to, and certainly won't today, win a popularity contest with Darryl Katz's buddy - and it has hurt his historical standing to some extent
Orr played a more vital, skill-demanding position (sorry, but try playing D, and then try playing center [I have] at the competitive level, and I think you'll quickly apprehend which position places greater demands upon its athletes. It's the difference between being a third baseman and being a middle infielder or even a catcher in baseball).
Both guys are naturalized Muricans these days, but only one guy always wished he was born somewhere else (like LA).
It's not at all outrageous, or even dubious, to suggest Orr is the best player in NHL history. It's beyond me why Larry Robinson, Serge Savard, Yvan Cournoyer, Al McNeil, Sam Pollock, and Jacques Demers all have it wrong, and people on this forum - most of whom have never made a dime in the hockey industry - all have it right.
Since I don't care for the Wayner, but have no axe to grind with anyone here (I'm actually an Oiler fan and root for them to have a big year next year), I'm not going to belabor this argument any further.
Wishing the Oilers a much better 2018-19 than 2017-18, and definitely hoping for another McRoss Trophy (which I expect to happen if Connor stays healthy and his team can be at least semi-competent).