While I hate to admit it, I would have to say that the most cramped configurations in Coach that I have been on were a British Airways 747-200 in the aft-coach section, and the new 777s that Delta has had delivered.
In BusinessElite, the 777 in Delta service is unsurpassed. But in Coach, the 777s are incredibly cramped.
Compared with the MD-11s that the 777s replaced, in Coach, with the exception of the bulkhead seats (god bless Gold Medallion status!) there is about two inches less space on the 777 - and that two inches makes the difference between an average height guy (5'10) sitting with legs straight ahead, or having to sit sideways, for fear of having your knees busted when the seat in front goes back.
The 747-200 in BA service wasn't much better.
But, on the other side of the coin, the best Coach seating I have come across was also on Delta, on a Delta Shuttle 727-200 that was on a mainline Delta flight from Tallahassee to Atlanta. The pitch was about 36" - very spacious indeed for coach seating!
Just my opinion!