I use graphene because I just like its way stricter security features, such as randomized numbers on the keypad when unlocking and it not having any Google services by default

But if you dont care about that and you would rather use MicroG (which is a little project that still runs at root access, but dosent send as much data to google) instead of G services just being sandboxed you can just as well use linaege

Also, linaege is a Team of volunteers that maintain many phones, as grapheneOS only makes Roms for the Google Pixel Series, so all their effort is towards the pixel phones. But as far as I know Graphene only maintains the Roms for phones that are still maintained by Google themselves, only giving a year or so extended support, but I dont know how long the Maintainer(s) that support the Pixels will maintain the Rom