Here are some quick tests have been doing with the free Maya rig; Mery, available here:
Mery is a collaboration project designed to give animators a really good quality free rig to experiment with. I think the design is a cross between characters from Disney's Frozen and Monsters vs Aliens.
A great rig, this is very flexible but capable of great subtly and emotion as well as comedy and drama (check out the demo reels on the site and on Vimeo)! The facial controls are detailed without being overwhelming.
Do check it out, it's the most enjoyable rig I have by far right now.