I have never used Solo, but I have used Anime Studio Pro (I actually wrote a review about it http://www.renderosity.com/news.php?viewStory=13450) and it's very intuitive and user friendly. For cut-out style characters, the rigging system is fast and easy (you just put the bones layer on top of your character layer and you're done).

You should definitely give it a try.

nemirc
Renderosity Magazine Staff Writer
https://renderositymagazine.com/users/nemirc
https://about.me/aris3d/