Crosby vs Ovi easily
Gretzky vs Lemieux sounds good in theory but it was never really a thing. Lemieux became great as Gretzky slowed down, and they rarely faced off, never in playoffs or such
Crosby vs Ovi started same year and have traded accolades their whole careers - and faced off in playoffs (on route to 4 cups) and internationally many times
Agree completely. Crosby and Ovechkin entered the league the same season and both scored 100 points. In all 4 combined cup wins they beat each other along the way in the playoffs, including that epic 2009 game where they both had hat tricks. There's the contrasts too, with Crosby being great at controlling play and tilting the ice during his shift, which Ovechkin's shot and hits can instantly change the momentum of a game. With their longevity, one might end up as the 5th best player ever outside the big 4, and the other as the all time leading goal scorer. I'll even go to the length and say this is the NHL equivalent to the Johnson/Bird rivalry.
Some of the other rivalries which I didn't think much of remind me of overrated player rivalries in other sports. Gretzky/Lemieux reminds me of Lebron/Kobe. Opposite conferences, very different play styles, and the age difference meant there were few single seasons where it was a legitimate debate for who was better at that moment. Thought Lemieux is closer to Gretzky than Kobe is to Lebron. Meanwhile, Roy vs Hasek reminds me of Brady vs Rodgers. The former one basically had a HOF career by the time the latter one became a starter, and usually had better teams around him, while the younger one was the better pure talent. Mostly opposite conferences too.
Similarly, you could say the Roy/Hasek rivalry overshadowed the superior Roy/Belfour rivalry in similar ways that the Lebron/Kobe rivalry overshadowed the far better Lebron/Durant rivalry. One last thing, when there was a debate in the late 2000's between the Sid/Ovie vs Lebron/Kobe rivalries, I said all along that the Sid/Ovie rivalry was better AINEC.