I got an email from Dropbox this week about this issue as seen in the image below. I have Dropbox on three computers, my phone and a tablet.

I use both Dropbox and Google Drive cloud storage. I use Dropbox for all non-Google app documents that I want synced to all my devices (this is the default on Dropbox) so they are there whether I am online or not.
I use Google Drive for all Google App documents and photos. I have a Google Drive "Legacy" account since I was an early adopter. As you can see in the image below, I only pay $5.00/yr and are only using 7% of my available storage. Google photos do not count against that limit as long as they are "High Quality" uploads (what my phone photos are uploaded as).

So, as you can see I may be rethinking my use of the two based on Dropbox's new costs (non now).