Flickr seems very popular but I couldn't make much sense of it so I use Pbase now. You do have to pay a small annual charge but I find this tends to sort out the more serious photographers.
But they aren't all fanatical professionals there. More like keen amateurs.
To give you an insight, here are my Pbase galleries
crustacean's Photo Galleries at pbase.com and if you click on the top line tabs you can navigate around the site and find whole world or just UK photos to visit.
I did find it a touch complex to start with as, like many sites, they have their own ways of doing things, but that was probably mostly stupidity on my part; and I quickly learnt to how to upload photos and pick individual backgrounds etc.