For quick testing during development I'd recommend setting up preview on a local network:
https://www.scirra.com/tutorials/247/ho ... al-network
As an alternative to Dropbox for testing your exported builds I would recommend BitBalloon:
https://www.bitballoon.com/
I've found this site to be a godsend - aside from the fact that uploading is a simple drag and drop affair, you can also customise the URL name and password protect it.