It'll depend on your requirements. Keep in mind that Nextcloud is the largest on-prem collab platform out there, so more users means more complaints... It is used in huge enterprise and government installations so it can definitely work, but it needs a decent setup. For a small company, use the Nextcloud AIO container I would say. For a big one, get Nextcloud Enterprise (starts at 100 seats) to make sure you get any issues addressed quickly.
I have only been using NextCloud personally with a single user but every instance I set up, there are basic problems like apps freezing, (and GH issue seems to have stalled some 6 months or so ago) and non polished interface really puts me off but since there aren't a better alternative, I use it.
Seafile is a close call if it gets more attention to remove rough edges and a bit more feature but interface looks more polished.
