Graphene OS - best privacy and security, only for Google Pixel phones
Calyx OS - less secure but supports cheaper phones (Motorola) and eco-friendly phones (Fairphone)
Honorable mentions are LineageOS, /e/ OS, Replicant and iode OS, however their security is much worse than of Calyx/Graphene (no verified boot), so use at your own risk
Graphene OS - best privacy and security, only for Google Pixel phones
Calyx OS - less secure but supports cheaper phones (Motorola) and eco-friendly phones (Fairphone)
Honorable mentions are LineageOS, /e/ OS, Replicant and iode OS, however their security is much worse than of Calyx/Graphene (no verified boot), so use at your own risk