For some people Dropbox may be the best option available, but I find it hard to believe that it is the best for the many that use it, considering the other available options.
As for my approach, it does require some work and knowledge to setup, in particular the server side (e.g. ssh, apache), and is beyond the abilities for the mythical average user.
The sync/backup runs are fully automated and don't require any action or knowledge from the user. I have this sync/backup approach setup in hundreds of systems (desktops, laptops, and servers) in several companies. Several friends and family also use this setup.
I have been unable to setup adequate encryption on Android and iOS so they are banned from the sync/backup servers due to the obvious potential for information leaks and security compromises. Phones being lost (or stolen) are a frequent occurrence.
edit: strive for better english