I have Fotki, Photobucket and Flickr. I find Fotki the easiest to make folders, move photos or even copy photos so you can have the same photo in two albums. I do that a lot when posting a photo on message boards. I have a Private album for message boards that I copy a photo into and then post it from there. That way if I should rearrange the original album, my photo will still be on the message board.
The links are easier to get on Photobucket. Without resizing each photo I couldn't get a post-able size like Fotki has.
I have never linked from Flickr so I'll test that here.
AzTom
32 Ford by AzTom2010, on Flickr