I grew up on a Gleaner L. Like most on this forum I didn't have a lot of experience with much else. Having used both I would say a Gleaner R is a better wheat combine than a 9600. Don't know to much about other crops. However, there are a lot of 9600's around that are still chugging along just fine and they seem very reliable.
I think that this thread should be titled best combines of their time. Because its hard to compare them when they are from a different time period. For instance in my opinion. The Gleaner L and L2 were the best of their time. When the 9600 came out it was the best of its time. I think a 2 series Gleaner became a better combine.... but just like everyone else around here, I have a bias.... Everyone will go with what they know...
Here is my list.... I do not know much about New Holland or Massey Ferguson so please forgive me. I am just going off our area.
Massey Harris 21-A
Gleaner A, C2, G
John Deere 95
Gleaner L,M
Case IH 1680
John Deere 9600
Gleaner R72
And I think its to early to tell on Deere 9870, Case IH 9120 and New Holland Equivilent, Gleaner S77, Massey/Gleaner/Challenger Axial.