I've been putting off exploring Eagle for some reason, but it's an extremely high-quality app. Beautifully crafted UI, everything is optimized for speed and efficiency. If you're taking reference / inspiration collection seriously, it's an indispensable tool!
I am very happy with Eagle because it is very fast and easy to use. I would like to have a native Cloud service, but the way it works I can have the files in any Cloud service like Dropbox.
Eagle is a godsend - I had reached over 700 images in a single Google Drive folder and decided enough was enough. Tagging all the images took time, but now my Eagle library is synced to Google Drive *and* I can sort through the images easily and quickly. The library is now approaching 1500 images and Eagle is so snappy that I have no expectations of performance issues.
Seriously, if you have a bunch of images that need tags, Eagle is it. Especially for a generous trial and one-time purchase.