My experience with Dropbox is that it is simple and easy to use and does not care what device you are using to access it. I still use the Google drive, but that is just non-photo files. Google has you save photos on Google+. I also use one drive from Micro Soft. This has proven so far to be a very simple and easy to use system that does not seem to care if you use Microsoft or Apple computers. I have not tried one drive on a mobile device or tablet so far. Google drive and Google+ are very good on android mobile devices. I also store some data and photos on Apples system. Apple is in the middle of changing their system so not sure what it will end up as. So far I have found Apples system much more confusing than Dropbox or One Drive. However, Apple did just fix their iCloud document storage system this week so that it seems to work better. And those are the ones I am currently using.
I give Dropbox a thumbs up. The photo lab that develops and scans my film pictures sends me BIG files using dropbox. Works splendidly.