I found a really cool tool, something I've been looking for a long time. It's called Eagle.
It is a piece of software that helps you collect images and media from the internet (even 3D files!), store and sync them via Dropbox or Google Drive and organize and tag them. It is pretty easy and intuitive and it has a very sleek design with advanced features that do not disturb too much.
You can use it for both Mac & PC -I use it on both whenever I'm at my workstation or my MacBookPro.
The drawback at the moment is that it doesn't have 'cloud' sync or a tablet / mobile version. Hopefully that comes soon.
Another advantage is that its a one-time purchase ($30), so, no subscriptions. It comes with 2 seats, and if you want more, you can purchase them for half price, or just deactivate and activate licencences, which is a bit of a pain if you have more than 2 locations where you use it.