Over all he's in the running, the post arcade and current online/youtube generation is weird. yes games are easier now, but they are also accessible to way more people and information is spread negative day one release.
There was a time during the arcade era that it took months for information to travel, it went from japan, to the US to the east or west coast then spread slowly from there. Being the best in your local area was all that mattered. The competition was a much smaller pool (but dedicated) and the games were harder with no practice mode.
To be good in that era you really had to be naturally good and get and sit on information and tech. Steel sharpen steel and it wasn't much steel to go around.
However the japanese always had a bigger and stronger network with there arcades and how dense the location was, so information got passed around quicker and they grew stronger than most american players.
So players like daigo and Tokido and other japanese top tier players kind of had a jump start
Over all I think, Sonicfox and justin wong are over all the greatest fighting game players of all time.
Until someone can win every single tournament they go to for almost a decade straight in one of the most aggressive and "cheap" games ever made. Its going to be hard for me to not place him at the top....
JW also plays all games well, I remember practicing Kof 11 for months then playing him in casuals and asking him how long he'd be playing and he said oh he does play the game really but likes the way the characters he plays looked... It was one of the most defeating moments. Like this dude doesn't even play really and is WAY better than me, and I've been playing grinding and learning the game inside out lol
Sonic fox is as consistent as JW but the competition he faces is WAY better than what JW did when he was running things. Which makes me want to give the title him.
Sonic fox is good at everything he places and places top if not wins it, just recently he played soul calibur 6 for the 1st time and got 2nd at a pre release tournament again a long time vet of SC...not that he's a slouch at SC he played 5 and was good. he also played DOA/skull girls and a ton of other random games.
I don't really care for him but he's a kid doing weird kid things.
his skill is undeniable though
TLDR
Justin Wong by a hair then Sonic fox