Okay I found four random pics of random models as a test, totally at random, and used the sites that worked/were free and easy to upload to.
These are in order of how good^H^H^H^H non-shit they were. IMGPILE puts a watermark on the image, which sucks but IMGBOX was a chore because it gave a URL for a useless thumbnail for some reason.
Postimage and IMGBB both drastically reduce the size of images for embeds, which may be an advantage sometimes, to be fair (I think it's better for posts like this on forums).
We'll see how long/how many of these images last before the host deletes them and replaces them with spamvertising.
IMGPILE:
IMGBOX:
POSTIMAGE:
IMGBB:
PIXELDRAIN:
[Useless - lets you upload then has a download limit. Ridiculous]
KEK - Didn't work for me. URL upload didn't do anything, normal upload just embeds a data URI in the page.
PUBLITIO - Doesn't seem to be an image host, or at least not like Imgur
FLICKR - Not practical. Always get a
Bad Panda anyway.
IMAGESHACK - You cannot be serious.