I personally am not ready to jump on the mesh heads yet. Not enough customization for my tastes yet.
As for mesh bodies, like someone else mentioned, it is all really subjective. It can come down to the body type you want, even the clothes you want to wear as some designers work exclusively with certain shapes.
Personally, I think Maitreya Lara looked the best on me. I tried Slink Physique but it just never quite looked right on my shape, but it looks absolutely amazing on my partner. Same with Belleza (sp?), the Mesh Project, even Kemono. Try demos of all of them and see what you like best for you.