re: Who is the best Auburn fb coach in history ?

As a very biased Alabama fan, I would rank Auburn's best head coaches in the following way:

1. Pat Dye
The man made Auburn football consistently relevant in the SEC. He also won Auburn four conference championships during his tenure and probably should have won them a national championship in 1983.

2. Ralph "Shug" Jordan
There's a reason why the man's name is on that stadium. He got the ball rolling at Auburn, winning the Tigers the first of two national championships while also being their all-time winningest head coach.

3. Tommy Tuberville
Sure, the man benefited from Alabama being on probation for much of his tenure, but while he was in charge on the Plains the Auburn Tigers absolutely dominated the state of Alabama in both recruiting as well as play on the field. Let's also not forget the prowess of that 2004 Auburn Tigers football team that went undefeated and won the SEC.

4. Gus Malzahn
While he might be in part responsible for the current state of Auburn football, one can't deny that he was somewhat consistent for the majority of his tenure. He got the Tigers to the national championship game in his very first season, winning the SEC in the process, while winning the West again in 2017.

5. Terry Bowden
Bowden's first two seasons as the head coach of the Auburn Tigers was an impressive 20-1-1. Unfortunately the Tigers were on severe probation due to the Eric Ramsey tapes and thus Auburn was unable to go anywhere to prove they were the nation's best team during that stretch. Nevertheless, when Auburn was finally off probation he guided the Tigers to their first SEC Championship Game appearance in 1997.