I'll be the contrary one: I tried a lot of things and ended up, eventually, going back to Nextclolud, simply because it's extendable and can add more shit to do things as you need it.
File sync and images may be all you need now, but let's say in the future you want to dump Google Docs, or add calendar and contact syncing, or notes, or to do lists, or hosting your own bookmark sync app, or integrating webmail, or....
It's got a lot of flaws, to be sure, but the ability to make it essentially do every task you might want cloud syncing with to at least a level of 'good enough', has pretty much kept me on it.