What are the most important / unusuall imporant features. Like a feature that is not required but is very important to you with your billing?

I think that intergration with a control panel to setup accounts automaticly and organized invoice sending with payment intergration. I also love coupons and I Think it is important but I can deal without its always something nice to have and I wish clientexec would get a feature for it.

what are you trying to say? you are confusing. I would have to say modern bill???