I think, in general, the ps4 community is more outspoken on forums online than the Xb1 community is. So there is an appearance that the communities are larger or more active. This in junction with the community tools on the PS4 make it hard to guage which community is “larger”.
Either way, i dont see the competitive scene going huge(lack of spectator tools, and stiff competition Overwatch, Paragon, For Glory, etc).
Still, i expect the ps4 community to outlast the PC and XB1 communities.
Im biased though…

just added it!
Gearbox says thank you to the ps4 beta testers, says nothing to pc and xbox testers.