#2 Ivan Lendl

When most players were busy using the serve-and-volley technique, Ivan Lendl was one of the very few tennis stars who focused on his baseline play.
He won a total of 8 Grand Slam titles and finished as the runner-up on 11 occasions - a record which is held by him till date. Roger Federer comes close with 10.
He won 7 out of his 8 titles in the 1980s. Just like Becker and Edberg, he never managed to win the French Open.
He has also coached a lot of tennis players, including Andy Murray and Alexander Zverev, whom he is currently coaching.
#1 John McEnroe

John McEnroe was known for his aggressive tennis and for his on-court behaviour as well, for which he has been punished on multiple occasions.
McEnroe was one of the best players of his generation, winning a total of 7 Grand Slam titles throughout his career. He, too, never managed to win the French Open. Additionally, he failed to win the Australian Open as well. 6 out of his 7 titles came in the 1980s. He also won the Tour Finals thrice and the WCT finals on 5 occasions.
He is currently a tennis pundit and a commentator as well.