Previously I was using various projects for these things like Coquelicot as a WeTransfer alternative but practically speaking Nextcloud is so easy to use (and relatively stable now) that I use it for most things that need to be shared with others:

* it's intuitive to use, so people who haven't seen it can quickly download what you send them without having to log in, being tracked and so on.

* password protection and expiry date for shared links come in handy

* superfast search is a boon for me as I have so many files it's probably the most important aspect

* the photos app in Next/ownCloud is underperforming if you have a large number of photos in a folder - the thumbnails seem to be generated each time I open the folder, it's probably a bug.

* when you need to collaborate, it's supereasy to add users and they intuitively know how to do things as they're used to Dropbox etc.