In terms of Lendl, while I think overall he has a stronger clay court record than the likes Wilander and Kuerten (I liked his achievement of winning 2 titles apiece at each of Rome, Monte-Carlo, Hamburg and Barcelona), and while he had the most dominant sequence at RG in the open era by a player other than Nadal and Borg from 1984-1987, I'm not sure if I'd rank his peak level at RG (from 1986-1987), at the same level of what I saw from the likes of Kuerten and Bruguera.
In 1986-1987, he largely played at RG as a defensive grinder, engaging in a series of long, seemingly never-ending rallies (a rally of over 100 shots was clocked during his match against Nystrom in 1987). He was generally more passive at RG than he was at the lead-up tournaments. Fair play to him he won both of those titles and was particularly dominant in 1986, although that strategy proved to be very costly when he lost to Chang in 1989.
His most impressive performance from start to finish at RG, was probably his straight sets SF victory over Wilander in 1984 (the most decisive victory by either player during their 4 matches against each other at RG). He really bullied Wilander from the baseline and pinned him back there that day, his backhand which Wilander tried to relentlessly target was on song, and his ability to amp things up with his forehand was decisive. His fitness levels, while improving, weren't anywhere near as strong in 1984 as they were in 1986-1987 (he was dead on his feet after the final and nothing left in the tank for Queen's the following week while Mac won the title there). That, meaning that he had to play more proactively at RG in 1984 compared to in 1986 and 1987, meant that he was far more enjoyable to watch during his first title run there (and the 1984 final is an all-time classic).
I guess though because Lendl was so strong on all surfaces overall, his peak levels on each of them can be overlooked. For example his grass court peak at Queen's 1990 was incredibly high in general let alone considering that it was on his weakest surface, on carpet he won Masters / YEC tournaments crushing Connors and Mac both in their primes back to back (after Mac had won 44 consecutive sets in sanctioned tournament play), and blitzing the other 4 members of the top 5 (including an in-form Becker on an official 21 match winning streak) in succession without conceding more than 4 games per set or facing and without facing single break point etc.