I hosted my First Nextcloud instance, on old Hardware, a few years ago for my sister, who wanted to Exchange Pictures with her scouts. Since then i converted the instance for my personal use and hosted multiple nextcloud instances for Business customers.

My recommendation ist to look wath you need in terms of availabillity and redundance. For my personal use it’s fine if the Nextcloud is down for a few days, but for a Business that can be fatal. If your requirements are Low you can opt for old Hardware on premiss, but you have to think about electricity and Internet Connection. If one of those is down your nextcloud is not accessable.

If you need a reliable solutuion i would recommend opting for a Cloud solution, so you don’t have to worry about Hardware, Internet and electrisity. Ether with Something like hetzner Share (i have no experience with Managed Nextcloud instances, but i know a company who is fine with it) or a VPS. If you are opting for a VPS, you should Look at storage Options, as Block storage is easy to Set Up but can be expensive if you need large ammounts of storage. Objectstorage can be a cheaper alternative, but it’s more complex to Set Up. Hybrid solutions are possible, for example with the external storage App in Nextcloud.

If you want to Host in premisess with old Hardware i would recommend looking at Energy prices as, old Enterprise Hardware can be quite powerhungry. Also you should Setup Hardware Monitoring so you get alertet if, for example a hard drive is about to fail or already failed.

And very importend think of your Backups. You need a storage to save your Backups and a Connection with enought bandwith. Trust me, you dont want to Upload 1 TB over a 16 Mbit/s Connection. Many Cloud Providers are offering Backup solutions, but be aware, you should have Backups in different Location as Datacenters can burn down to, as we saw a few years ago in france.

The perfect solution doesn’t exist. You have to Look at what you need and what you can afford. IT-Intrastructure always costs something. If it’s Not Money, it’s time, energy, electrisity or Something else.

I hope this was helpfull.

As far as operating systems goes, i would recommend Debian or Ubuntu. These are very wiedly used and there are many resources. And if you are brave, you can start without a Desktop.