KitchenOwl and Pastes are probably the easiest to setup. Paperless is the most useful for me. Nextcloud can be a bitch to setup once you want to include Office functionality. I recommend the Nextcloud All-In-One to make it a bit easier.

In addition to the ones listed above, I can also recommend Home Assistant if you don’t know it yet. If you like home automation you’re in for a treat.