Why is that? Have been using NextCloud in our company and for myself, and I couldn't be happier, no issues since 3 years, all the tools and plugins I need, sync running perfect and hassle-free and performant. I thought it's generally liked up until now - I didn't try any of the alternatives though, so they might indeed be better. Though I don't have any reason to try them tbh, as NC works almost too well.