I like the the hidden world one. I think you could develop that one into a very detailed roleplay if you keep consistent with your plot and monitor the roleplay constantly.
I just prefer anime pictures because I watch anime a lot (Too much lol)
However, I have a strong distaste of using real pictures. I think me personally, I see enough of 'real' that I like to be able to get away from that and just use my imagination and go wild.
If I use a real picture, I...