There isn't a replacement for CentOS 7, it's still a supported product by CentOS/Red Hat. You can keep using it for another 2 years in fact. If you want to upgrade CentOS 7 to the next release then you have a couple of choices - you can use Red Hat Enterprise Linux 8 under their individual developer program on up to 16 machines for free. You can use CentOS Stream 8 (or 9) which is a rolling update upstream of RHEL 8. The best replacement for CentOS 8 which was downstream of RHEL 8 would be either Rocky Linux or AlmaLinuxOS. Either work perfectly fine and outside of branding are identical to CentOS 8.¹⁾