Just saw that this thread has been revived! I actually have been using flickr and love it way more than photobucket (even when photobucket was decent). I haven't looked at the other recent suggestions, though.
Oh....just tried Hermana Linda's suggestion of https://postimg.org/ and I like it. It's very basic in a functional way meaning....it's a service only for posting images. Basic and intuitive. As opposed to flicker which has a bunch of other functions, but posting images takes several more steps.
I used the 'thumbnail for forums' option for the gratuitous 90% eclipse photo above!