I thought Cloudflare was going to win the image hosting/serving/resizing game based on their original blog post, but that doesn't seem to be the case.
I kept getting frustrated with the complexity and changing costs of solutions out there, so about a year ago I launched https://www.simplefileupload.com. It's a super easy, flat rate cost solution to quickly allow users to upload images and files. It provides a customizable upload widget and serves files via a CDN and firewall to protect against attacks. It doesn't have query param image resizing yet, but it's coming!