Kayako. Support and even more. Great internal communication system.

I would have to say I was surprised on how much I enjoyed working with Kayako. Fairly easy to program (learned it 100% self taught), reliability was nice, customer service/support was always great. Check the hours their support is open. Make sure you know "emergency contacts" for them. If using SAAS remember it's a shared server and someone you share it with could cause downtime through overuse or attacks on system. This only happened a few times but they are pretty good at being reactive to servers being down.