I think football is much more difficult to determine who the GOAT is and what a player means when you have club competition and international competitions where there are so many more variables.
In basketball you got the NBA, in American football you got the NFL, baseball-MLB, hockey-NHL(lesser extent the olympics/WC) where there are less variables.
There are basically a handful of GOAT's to people in football and you can make a legit argument for them all.
In basketball you got Jordan with a small(and weak) case for LeBron. American football is by position, hockey(Gretzky with maybe weaker cases for Mario, Orr, Howe)