You can easily selfhost Seafile and make a ‘dropbox’ like system with as many users you like, and as large a storage you can handle / afford. Although there is an enterprise version, the community edition provides with many features to make it really a great service. It is mighty fast, and has native clients for many different platforms, in addition to using the Seafile website to acces, upload and download files.
I never hosted Nextcloud, but from what I read, it is a beast with way too many features to fit my use case. Seafile is doing one thing very well.