Each of these have their own pros and cons.
Dropbox has a few features that are nice. Selective syncing and network control are the two top ones. But the biggest con is if you have multiple dropbox accounts. For example, you could have a personal account and one for business. Switching between them isn’t very friendly, and while yes, you could share the folders in your business account to your personal, that isn’t always the best solution.
Google Drive has the same multiple account issue, but the biggest issue is speed. Syncing a large amount of files just kills your computer and network. I’ve never encountered this issue with other syncing services, and makes it almost unusable. It does feature selective syncing, but turning off a folder really slows things down again as it syncs.
Box works similar to Dropbox, but handles the multiple accounts better. It creates a new box folder labeled with the email of the other account and lets you switch seamlessly. It also has the selective syncing of Dropbox, but it doesn’t have the network control that Dropbox has.
In all, none of these are perfect. But if I had to choose, I’d probably go with box simply because of the ability to handle multiple accounts better, but really that’s depending on your personal preference.
Right now, I run both dropbox and box on most machines and that works fine. I can go between the two cloud drives to get what I need from each quickly.