I would say that AEW has the better roster in the sense there's more people positioned to fill spots if people higher on the card get hurt and/or leave. In WWE, they're pretty much fucked if Roman decides to go make movies or whatever full time. Even though they have a ton of people on the roster, you can count the folks who could realistically be put in a top spot on one hand and have fingers left over.
Now WWE has shown they can heat someone up and put them in a main event spot on a temporary basis, but they've also shown they don't stick with it and that the person ends up back in the same position they were prior to the push.
I suppose this will be AEW's big test since Punk was their biggest draw and he's going to be out, but that's just going to open the door for folks who have been somewhat downplayed as of late.