Coogler is a damned good director, but I'd say action is probably not his strongest area. Joss Whedon is a servicable director, but works because he works what audiences want to see.
James Cameron is better than both and I don't even really like Avatar.
Lord no. He's definitely up there, but the best? I think Bay is stronger when he's not shooting Transformers films. Cameron is up there and he's one of the longest in the game, because John McTiernan flamed out due to legal troubles. Miller made it look effortless in Fury Road and other Mad Max films. I'd probably put Takashi Miike up there. There's also a solid next level that includes directors who specialize in other things, but can direct great action: Spielberg, JJ Abrams, Ridley Scott, Tarantino, Kathryn Bigelow, Edgar Wright. Gareth Evans has to show me if The Raid and Raid 2 are all he's got.
Lord save us from these takes. Spielberg been slumming it so long that folks have forgotten how good he can be when he's not doing serious dramas.