Someone on github has a decent comparison of a bunch of different backup solutions. Afaik Kopia generally uses more memory but is the faster, and restic is pretty fast and doesn’t use as much RAM as kopia (for awhile people recommended against restic as it lacked compression, but they added it in 0.14 last year).
I personally prefer kopia (has a gui to help configure it), but restic is also good. I’m not a fan of Borg because you can’t backup directly to object storage (eg. Backblaze B2/Amazon S3/Wasabi/etc), you have to backup to a local or mounted drive, then upload the backup.
I’m also waiting on github.com/rustic-rs/rustic to get better windows support, as it should use less memory than restic while being as fast, or maybe even faster.