I used them all with multiple devices.
Indeed Graphene is the most robust and I like also the easy updates that come with it.
And you don't need to have the latest pixel model if your budget for a new device is not large.

Here some other tips to count on when you go on this path
https://darth-coin.github.io/beginner/bitcoiners-mobile-device-en.html

Good to know. I'm probably going to get a pixel, though. So it seems that I may give Graphene a try. 

Scoresby

Also you didn't mention LineageOS, that I find it quite good for a non-pixel phone.