Fetisov would be a valid answer.... If Gretzky didn't exist.
If Trottier or Lafleur didn't exist.
Before Gretzky joined the NHL, the 3-year-older Fetisov had been top defenseman at the 1978 world championships over the 3-time winning quality Czechoslovakians. Then in 1979 Fetisov was a point per game in the Soviet league and his play so impressive he would be named captain of the national team by year's end.
In 1979 the greatest player may have been Fetisov.
Yeah, Trottier won the Hart, but Bossy scored ten more goals than anyone else with 69 whereas Trotts had just 4 more points than Dionne. In the 1979 playoffs young Trotts had just 2 goals and 4 assists on a conference finals run, bounced by the Rangers.
In 1979 Lafleur had his lowest goal total in five years, his 52 was 3rd in the league. Led the playoffs in points, though Gainey got the Conn Smythe (Robinson had won it in 1978).
So,... perhaps the 1978-79 period could have been one where Fetisov was the greatest, which North America had yet to learn, and Fetisov's 1980-1982 period one where Europeans thought Fetisov the greatest because they had yet to learn how great Gretzky was.
It was pre-Internet, pre-cable TV. You either watched a game live on a network carrying it or else you missed it and had to settle for highlights during the news hour. So, comparing greatness between Russia and North America back then was difficult outside of international tourneys like the Summit Series and Canada Cups.