isn't flickr intended more for personal stuff? (i would prefer self-hosted owncloud in this case anyway)
i see imgur as just a "tool" for uploading and linking arbitrary (public anyway) images, and the right tool at that for this purpose (although they offer accounts too)
This is what I thought too.
I never use Flickr, but the only time I use Imgur is to upload images to places that I need a link to upload (such as this forum). I don't have an account and don't have anything saved on there.