I think the question already says it all. I know there exist animals that have both herm and female populations and other's with herm and male populations, I'm not personally aware of any animal that has herms, males and females but I suspect that also exists somewhere. I'm just curious which of these sex combinations is most common, ie which is most likely to evolve.
If you could also speak to why one sex combination may be more prone to evolve over another I'd be very interested in that, but I'd settle just for knowing which combination is more common.
I'm asking specifically about simultaneous hermaphrodites here, I know sequential hermaphrodites exist but that would just complicate the question.