Easiest would be entire folder, ensure's you do not miss anything relevant and also get the storage config, which let's you also start a bit faster after the reinstallation.
For a single standalone node, I'd in all cases save and restore (single node only!)
Code:/etc/pve/qemu-server/*.conf /etc/pve/lxc/*.conf # storage cfg /etc/pve/storage.cfg # backup jobs /etc/pve/vzdump.cron # firewall rules/options /etc/pve/firewall/*.fw
Thanks, will let you know how it goes. Thanks for all your help.