Finland's 1995 World Championship win over Sweden would definitely be No. 1 for that country. Slovakia's big one would be winning the 2002 World Championship.
1972 was definitely bigger than 2002. 1972 was supposed to be an exhibition, but it turned out to be much more than that. It had a level of intensity and significance that has never been matched by any event in hockey. 1972 is the single-most important event in hockey of the 20th century, not just for the level of play, passion and intensity, but for the importance to the game as a whole. It was the eye-opener for Canadian hockey and the rest of the world. From that point on, the Soviets were regarded as Canada's equals. Never again would anybody predict Canadian domination in a true best-on-best. If 1972 was just an exhibition, then Phil Esposito was prepared to kill another human being over an exhibition.
The other aspect that sets apart 1972 from the U.S. Miracle on Ice, the Canada/World Cups, and the 2002 Olympics is the scope of the series. Those were generally best-of-one tournaments (or best-of-three's) in a fixed location. 1972 was an eight-game war. It was played in both countries. You had the fan interaction in Moscow when 3,000 Canadian fans travelled to support their country. You had the mysterious phone calls to Canadian hotel rooms in the middle of the night. You had Alan Eagleson trying to throttle a Soviet goal judge when the red light didn't turn on after the fifth Canadian goal in Game 8. You had the backstage politics. 1972 had it all, and it's something that has never been matched.