My understanding is Calyx is (or was) a little easier to work with apps that require Google Play Services. Graphene may be better now though - they added a sandbox element a while back.
Discussion
Yeah with Graphene today all you need to do is open Graphene's app store and install the sandboxed Google Play Services and that's it, done.
It used to be a lot more tricky but for the past year or so it's been easy af.