Also I like Dropbox because they keep it stable and do not needlessly fiddle with it.
It seems like the other cloud storage services are always making little edits and tweaks, and sometimes not so little, to how they function and how the user interface works.
That annoys me very much. Once I learn how to use a piece of software, I want the user presentation layer never to change again ever in my lifetime.
I hate having to relearn something like that. In having to figure out the new thing, the cost in time, attention, and interruption of whatever I was trying to get done is almost inevitably much greater than whatever tiny benefit the "upgrade" yields, if any at all.