Gotta go with Mac easily, from my POV. Mac's indoor and WCT wins *alone* put him ahead, setting aside for the moment his two more Wimbledons and how he won them.
Yes I think it’s a comfortable lead for Mac over Agassi. Agassi IMO is by far the easiest open era legend to rank - he was clearly not as great as any of Connors, Lendl and Mac, and was clearly greater than any of Becker, Edberg and Wilander.
Mac’s second best season in 1981 during which he dethroned Borg, won the big Wimbledon-US Open double and led the USA to Davis Cup glory (the Davis Cup was no less important than Roland Garros was then), was more impressive than any season that Agassi had IMO.
Throw in the fact that he clearly beat better players to win his majors than Agassi did, was dominant at both of the 2 majors that US players clearly care about the most while Agassi was dominant at neither, had the best record in 3 different seasons (1981, 1983 and 1984) compared to 1 for Agassi (1999), was a greater Davis Cup legend, was a much greater indoor player, won more titles overall etc, and it’s a definite win for Mac there.
Weeks as world no. 1 was not a serious metric before the formation of the ATP tour in 1990, but Mac was clearly the best player in the world, and a top 2 and top 3 player, for longer than Agassi was. Agassi finished as the year end no. 2 behind Sampras in 1994 and 1995, but Mac was the second best player in the world behind Borg (more dominant than Sampras was) in 1979 and 1980, so ‘Agassi being denied by Sampras’ is not a serious factor here.
I would put Mac over Jimbo too.
But I value peak level over longevity.
I think that Mac has some big advantages over Connors, and I’m inclined to agree.
Mac unlike Connors was dominant at Wimbledon, so therefore was dominant at both of the big 2 majors at the time (there’s a Legends of Wimbledon episode / film on Mac but not on Connors - Wimbledon was clearly the undisputed no. 1 major for a while), was a Davis Cup legend while Connors is the only open era great not to properly win the competition (to repeat the Davis Cup was hugely important then and no less important than RG IMO), was a greater indoor player (indoor tennis was hugely important and made up a large % of the circuit during their respective primes), and his 1984 season is greater than any season than Connors ever had (including his 1974 season - it is usually, rightly ranked ahead there). And Connors winning 8 majors to Mac’s 7 is not a serious factor, given that they both won 7 Wimbledon / USO titles, with the difference Connors’ lightweight AO title in 1974 (both players won numerous other titles that were more noteworthy than that). That’s without even considering doubles.
I’ve always rejected any notion that Connors and Lendl are far greater than Mac, and there is no case for Mac vs. either of them. If we actually compare them based on the conditions when they were in their primes, and not on conditions from the 90s or 21st century, there are clear arguments for Mac. If we go back 30 years to 1994 for example, it was a widely held view that Mac was greater than Lendl. Since then the majors have become more equal to each other, the major count has become the be all and end all, weeks as world no. 1 previously not so important has become more of a big deal etc., so opinions have shifted there, but largely based on conditions from later periods.
