I have used Fotki for the past 10 years and have over 400.000 images there, they have the best interface in my opinion. Very flexible design with features most people never even get to! Their pricing is also the best for what they offer.
A few months ago I also started an account at Flickr, partly to have a secondary source for all my images and I like their slideshow feature better for Blogs.
I have looked at all the hosts over the years and those are my choices, Photobucket is free and I guess is fine for the casual user but their servers are slow to deliver images and you generally get a lower quality service.