I loved Tresorit but it's camera upload feature didn't transfer files correctly from my wife's iPhone - it left them corrupted and unopenable with no warnings or errors whatsoever.

Unfortunately because of that alone I dropped them completely. I'm using Dropbox now because I haven't found a better alternative for syncing between iPhone/Android/Windows/Linux.

what things that you need synced

It's quite expensive though

Yeh true but as an other example Dropbox missed out on the privacy and end to end encryption market.