If you meet all the requirements, a BTA or RBTA are usually considered the easiest to leep. However, for many, the best choice might be no anemone at all.
If you are only wanting one for hosting possibilities and aren't having pure desires for the Anemone alone, then maybe look into some of the easier corals that will also host.
If you are interested in hosting make sure the clown and nem are compatible. I have an rbta and Colorado sunburst bta and my black percs show zero interest in hosting them or any other object in my tank.