For nextcloud I would recommend using the all-in-one setup, but as far as email you might want to use an already existing solution rather than trying to host it yourself. I would recommend protonmail for your email since all the other common options like Microsoft and Google are not privacy respecting.
Ubuntu LTS server. I chose it because it's got good support both in community and enterprise support. Also it's pretty simple to use and almost forgot it's got zfs built in.
For nextcloud I would recommend using the all-in-one setup, but as far as email you might want to use an already existing solution rather than trying to host it yourself. I would recommend protonmail for your email since all the other common options like Microsoft and Google are not privacy respecting.