The problem with Dropbox for me was that it didn't even allow me to buy enough storage space.

I wanted to be able to sync my entire reference files so that I could (1) use it as back up, and (2) reliably access any files I needed.

Google Drive offers much higher capacity (i was using 200GB, and recently upgraded to 400GB).

That said, Google Drive's features aren't nearly as nice as Dropbox - dropbox is just incredibly slick. I love the features like simply right clicking on a file on your desktop and getting a public link to it. To do the same sort of thing in Google Drive takes about 5-10 clicks and about 2-3 minutes. Definitely not 'fast and fun'!