Don't see how the atos game is better for a bigger guy (I am 6 foot 3 tall and prefer the AOJ style). Galvaos style works best for being being explosive and stocky. It's simpler stuff so I agree that it can be easier to pick up.
Atos online had a wide variety of technique. They had a bunch of their top competitors doing guest instruction which is/was nice.
AOJ seemed Lazer focused on the probably light or feather and lower game. Mostly reverse dlr, berimbolo, ect.
I haven't subscribed to either in a couple of years to be honest so just going off memory. Things could have changed too.
Edit-. Even the way their competitors were distributed- it seemed like anyone below middle was probably Aoj, above probably Atos.