Bob Marley and it ain't even close since James Brown's Era stems mainly from the Era he was alive in and influenced. Bob was legendary Status after the labels brought him to America and Beyond when he was alive and after he died, that shytty Legends Album found it's way all across the globe from Japan to Luxembourg. The amount of casual reggae listeners that know Bob Marley as opposed to James Brown is staggering. Brown had a way bigger influence, though, since he influenced movement.
The beautiful thing about Reggae music back in the day is that NO ONE WITH SENSE making Golden Age Reggae wanted to be a Bob Marley clone and got influenced by it to the point of biting or at times, even starting out to make their own shyt. Reggae was always a movement that they got behind off of the Culture and the multitude of excellent Reggae stars that came before bob and stood with him. He helped pushed the music and movement into the Stratosphere though.
If the two were playing a "Back from the Dead" One off show and I only had the option to attend one, without blinking, I'mma get on my good foot and go see James rather than Bob. That's on everything.