We've compiled a neutral list of blog posts indicating the pros and cons of both systems.
CloudAstrix SPE v0.5 was based on Asterisk, and we've made the move to Freeswitch in v1, and never looked back since.
We had many reason to, but you can decide for yourself after reading some of these comparison articles from reputable websites.
http://www.whichvoip.com/freeswitch-vs-asterisk.htm
https://freeswitch.org/how-does-freeswitch-compare-to-asterisk/
http://www.richappsconsulting.com/blog/blog-detail/asterisk-vs-freeswitch/
http://gonorthforge.com/a-comparison-of-voip-platforms-asterisk-vs-freeswitch/
https://starpoundtech.com/asterisk-vs-freeswitch/