Please don't take this as fact but my feeling after less than 24 hours is that while Graphene has more frequent updates CalyxOS might be more stable. That could be untrue and maybe a small sample size but that's what I'm feeling right now. There's always tradeoffs.

I like that Graphene doesn't come with a bunch of apps like CalyxOS. CalyxOS isn't bloated but Graphene is sparse.