I have been on Opalstack since they started. I like them. I pay for hosting monthly. I’ve self-hosted several apps there (or tried to, sometimes; I couldn’t make everything work all the time). Nextcloud is dodgy; I like it, but it’s a pain in the ass for someone like me (not a dev, not a coder) to deal with the almost inevitable problems every 2 or 3 times I need to upgrade. And I’ve never been able to get an office suite working well. Much of this could be because I’m trying to run NC on shared hosting; even opalstack’s support doesn’t fix all of that.
Email: opalstack has email. I use it. I don’t actually know what service it is, but I have three or four mailboxes linked to a couple of domain names I own, and several hundred email addresses* Thunderbird does great with IMAP on my laptop, desktop, and phone, with opalstack as the server.
*lots of emails because when I sign up for something I create a new email address just in case they sell my stuff and I start to get spam.
I don’t think that works on shared hosting (at least not without similar workarounds and tweaks), but I hear that the AIO method and snap both work really well if you have root access on the machine.