My top 10 list (not in a definitive order, but in a sort of order):
Tikkanen-Gretzky-Kurri (Edmonton Oilers)
Aka Finnish Sandwich. I don’t know if it was even the best of Gretzky’s lines, but a very well balanced version of the Oilers’ top line it was in my opinion; one offensive wizard and best playmaker of all-time, one two-way player with a lethal shot, and one, well, nutter. (No no, Tikkanen was a fine all-round player.) They were a joy to watch and a nightmare for the opponents in the mid-/late-‘80s. Not just in the NHL, but they also had a strong performance vs the Soviets in the 1987 Rendez-Vous. Gretzky and Kurri (or sometimes Tikkanen?) were also a dangerous pair on the penalty kill.
Krutov-Larionov-Makarov (CSKA Moscow, USSR)
KLM. Maybe the best line of all-time? (At least if the we talk about the whole Green Unit.) Played together from the 1981-82 season to 1988-89. Rarely played a poor game or a game where they didn’t score, no matter who they faced. I’m glad that in recent years Sergei Makarov has finally gotten the appreciation he deserves; he is one of the best forwards ever, period. I’ve never been overly high on Larionov, but no question that he was a skilled, smart player who took care of his defensive duties and who fit in well with his more explosive wingers. Krutov was equally at home in speedy skill game as well as battling with defencemen in front of the net, a terrific goal-scorer. They certainly got help from their steady defencemen (especially Fetisov), but were by no means dependent on them. Notice also Krutov and Makarov’s terrific penalty-killing tandem.
The greatest goals scored by the Green Unit
Gillies-Trottier-Bossy (New York Islanders)
Trio Grande. A personal favourite of the North American lines, not sure why. Despite one player being clearly inferior to the other two, it was still in other ways a well-balanced forward line; Bossy was one of the greatest goal-scorers of all-time and a pure ‘finesse player’, Trottier a physical two-way player and playmaker, and Gillies a huge physical presence who could also put the puck in the net and pass it too when needed. Obviously they got great help from Denis Potvin also. Their success in the NHL and contribution to 4 Stanley Cups needs no further introduction, but they also had some strong and productive international performances, like the 1981 Canada Cup (despite the disastrous final for the team), and the first two games of the Challenge Cup (basically Team Canada vs USSR).
Shutt-Lemaire-Lafleur (Montreal Canadiens)
Dynasty Line. I guess this version of the Habs’ top line of the mid-/late 1970s was the best rather than the one with Pete Mahovlich instead of Lemaire? Lafleur was the obvious superstar offensive dynamo, Lemaire a speedy two-way center with also reputation of timely goal-scoring and Shutt - forgive me the term - a pure goal-scorer. Very fun to watch (much thanks to Lafleur), and I guess mostly they could pretty much concentrate on the attack, with players like Robinson and Savard, or Lapointe, on defence.
Kharlamov-Petrov-Mikhailov (CSKA Moscow, USSR)
The KLM of the seventies. All in all, played about 11 years together. Mikhailov, Kharlamov and Petrov hold the number one, two and four spots, respectively, in the World championship scoring. Kharlamov was the biggest talent who could make devastating plays and score devastating goals, Petrov a strong two-way center with big slapshot and good passing skills, and Mikhailov the most productive goal-scorer with also a physical side (and sometimes downright nastiness) to his game. They never had a top notch defensive pairing who played behind them on the national team year after year (Vasiliev-Gusev was probably the longest-serving one). Somewhat unfortunately, the trio didn’t play together in the 1972 Summit Series, except for a few power plays. In the 1975-76 Super Series vs NHL teams, they played (very productively, I might add) in the first two games vs the Rangers and the Canadiens, but the last two games against the Bruins and the Flyers was with Maltsev at centre. In the 1979 Challenge Cup, Kharlamov was injured already in the first game. This is probably why they are not quite as famous in North America as in Russia/Europe. Petrov and Mikhailov were also heavily used penalty killers.
Kharlamov - Petrov - Mikhailov
Leach-Clarke-Barber (Philadelphia Flyers)
LCB line. According to Clarke, at one time Scotty Bowman considered this the best line in the world (around 1975?). In any case, while Leach and Barber were not exactly slouches, I think it is fair to say that the greatness of this line rested fairly heavily on Bobby Clarke’s shoulder. He was not only the top defensive player but also the top offensive player (though actually the weakest goal-scorer) of the line; quite a rare feat. Leach’s main contribution was his scoring, Barber had some versatility. In addition to their work in the NHL, they also played in the 1976 Canada Cup; overall, their performance was a disappointment in the tournament, but the line still deserves some credit for their timely scoring in the important round robin game against the Soviet Union and in the 2nd game of the final against Czechoslovakia. The line had a big performance against CSKA in 1976 too.
Lindsay-Abel-Howe (Detroit Red Wings)
Production line. This was the best version of the line, right? I’d say on paper and the most dominant at least. In any case, it is the wingers who mostly made any version of the line legendary. Howe was obviously the best player and at least eventually the best goal-scorer as well as playmaker of the line. Well, the best at about everything. Abel, as the clear senior of the trio, probably had an important nurturing role in the beginning and was occasionally even the best performer of the three, and Lindsay was a small but nasty instigator with good goal-scoring and playmaking skills. Skill mixed with toughness, old-time hockey, yeah!
Hodge-Esposito-Cashman (Boston Bruins)
The Intro Line (one of the nicknames anyway). Not among my favourite lines of all-time per se, as they represented the ‘dump and chase’ hockey too much for my liking, and it also has to be one of the worst-skating and slowest top lines ever, but one cannot dismiss their very high productivity in the early 1970s. Cashman was one of the best ‘cornermen’ ever, feeding Esposito, who was possibly the best slot man in the history of hockey. Esposito might also be somewhat underrated as a passer/playmaker. Hodge and his role on the line is somewhat more obscure for me, but he was a big man who at least occasionally used his size to his and his team’s advantage and could both score and set up goals pretty well. Bobby Orr’s big influence on this line cannot be forgotten either. Esposito and Cashman did not only show their power in the NHL but also the Soviets had problems with their mastery of dump and chase and physicality in the 1972 series (games 2 and 3).
Lemieux-Francis-Jagr (Pittsburgh Penguins)
They didn’t play very long together, and didn’t even win a cup, but Lemieux and Jagr (and to lesser extent, Francis) on the same NHL line had to warrant a place on the list (I also considered the Stevens-Lemieux-Jagr line, but Jagr wasn’t quite a superstar yet back then). Lemieux and Jagr are among the best scorers and players of all-time, while Francis added some defensive game to the line, with good playmaking too. Despite the big size of all three players, the line didn’t appear to be overly physical, but it’s not like they could be bullied either. I think they might have had the biggest scoring potential of any line ever, but unfortunately their time together was fairly short.
Blake-Lach-Richard (Montreal Canadiens)
Punch Line. Shined and dominated the scoring during/a few years after the WWII. Richard was the superstar and one of the greatest goal-scorers and one of the most dangerous players from the blueline in ever. Lach was a tough and hard-working playmaker who won the scoring title twice, and Blake completed the line with also prolific scoring, strong playoff performances and leadership qualities. Blake's injury ended the line's dominance in 1948.
Sorry for the possibly somewhat superficial characterizations of some players and/or their roles at times. You can’t always get everything right.
I also thought about e.g. G-A-G line, French Connection, (Punch line), Kraut line, Winnipeg Jets’ Hot Line (or at least some line with Bobby Hull), and whether players like Crosby, Ovechkin, Béliveau, to name a few, and any of their lines could be included. I considered some of the legendary Czechoslovak lines, like B. Stastny-Novak-Martinec, and some other European lines, but it would have been a bit of a stretch to include them in the top 10. Possibly I favoured the 1970s/1980s too much.
Suggestions, links to highlights, whatnot?