I would have to say maybe Crosby, but probably Malone. There is a certain mystique to Malone due to his 7 goals in a game and ppg numbers, but I don't think you can even argue that he had a better career than Stastny,let alone what Stastny had to go through to play in the NHL. I remember reading somewhere where Malone states that the modern game(1950-60's) was not even close to the game he played, in terms of stamina and skill. A great player for sure, but I don't think his short career or skill level is close to Stastny's.
Trying to clear up some of the misconceptions here.
Short career: Malone played ECHA/NHA/NHL hockey from 1909 to 1924. Even if you take off the last two years when he didn't play much at all, that's 14 seasons at the highest level of the game. Stastny played 13 full NHL seasons.
You can't just look at Malone's NHL career. The dividing line between the NHA and NHL is arbitrary and simply the result of politics. You can't ignore his 7 years in the NHA just because Eddie Livingstone didn't get along with the other owners.
Mystique: Malone does have a certain mystique, because most current hockey fans don't know how to interpret his numbers due to the differences in the game between then and now. But let me tell you as an expert in this era: his 44 goals in 1918 is genuinely impressive. No, it's not the best goalscoring achievement in history, but it's very impressive nonetheless.
Skill level: 1918 is not Malone's only good year. He led the NHA/NHL in goals
four times in his career, having three other seasons very similar to his 1918 performance (1913, 1917, 1920).
And as an aside:
Old hockey players never die: Of course Malone said the modern game couldn't compare to the game in his day. All retired hockey players say that.