I just moved my files from nextcloud to seafile, founded that I don’t really need chat, calendar, tasks and other things, only need to store files and have it synced between my devices.
Nextcloud works for my small company and I’m not going to change it for now.
3 years and counting here, I host my own company email and a couple of clients, 120 email accounts and only had one issue with a compromised account, limit each domain to 100 sended emails and I can catch spam emails with enough time before my vps provider notice anything