If you compare just singles it would have to be Agassi. But overall as a tennis player, playing doubles and singles it would have to be Mcenroe. I defintely think in both their primes on any surface Agassi would knock Mcenroe off the court, very easily. Too much power and pace, even at Mcenroe's prime. You can even see this since '85 when Lendl finally figured how to beat Mc's volleying by overpowering him and lobbing him. And Agassi was pretty much a clone of Lendl.
Good post. I think if you look at their competitive careers, its about even. McEnroe came up at the perfect time for him to rise to the top with a left handed serve and volley touch game. He just got better and better until he peaked in '84. Up to that point, I feel that he could have beaten any player the world on any surface. Then the power baseline game started to rule the game and McEnroe did not have the means to handle the pace and topspin of the players like Lendl, especially on slower surfaces.
Agassi, also came at the right time. I agree, he adopted Lendl's power baseline template, but took the ball earlier and used the ultra stable 2hbh to control the ball from inside the baseline. His talent from the baseline allowed him to play for 20 years and stay competitive in the sport until he hit his last ball.
McEnroe is still a bigger name in my opinion, as he has continued to stay in the game through broadcasting. McEnroe also had a more unique game than Agassi, that will probably never be forgotten or duplicated. But, Agassi has done more to advance the style of tennis we see currently. 90% of the guys on the tour are playing Agassi's basic power baseline game. Agassi was very influential in that respect.
Competitive career: push
Unique game style: McEnroe
Influential game style: Agassi
Head to Head: Agassi
Historical Value: McEnroe
That's how I see it. I like McEnroe more, so I could say McEnroe is better. But honestly, I see them as dead even.