Should we consider strictly helpdesk solutions? not actual billing systems with a built-in helpdesk. Following my experience with both Kayako and FreshDesk, I can tell, FreshDesk accomplished incredible job in making their helpdesk solution very easy to use, super friendly, I really can tell that. Besides being very friendly and easy to use for the agents/staff, they have all the features I personally needed during my work with it, canned replies, automated scenarios, flexible and automated ticket dispatcher module and those who also offer social media support, they have great twitter integration right inside FreshDesk admin level, so you can either reply to twitter directly from FreshDesk or convert twitter posts into tickets and reply to your clients this way. So, while considering a solid helpdesk solution, certainly check them out for features, test their demo and decide for your self - after-all, it's just my opinion.