Multi platform software recommendation for laptop backups to remote self hosted server ?

Almost everything is the title I think. I have a Proxmox server at my friend's place, and I want to automatically backup my most important data there. I'm almost never connected to the LAN except through a VPN tunnel. 

What is the best practice and software which corresponds to my needs ? I have seen people mentionning Borg and Duplicati but I want to be sure that I don't miss a new standard :)

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Thank you for your help guys !