Switched all my devices from a Dropbox paid plan → Syncthing since Dropbox decided my filesystem isn't good enough. Really impressed by the quality of the software so far, things Just Work™ and seem to support the features I care about! Now just needs iOS support... :-)
Yeah iOS is not really a deal breaker for me, the only thing I was regularly syncing with Dropbox was my Keepass database anyway... and that's mostly read-only from my phone. Photos go into Google Photos, and I don't create many other files from phones :)