Which of the two above should I get for my hosting? Pros and Cons of both please.

What do you need out of a billing system?

paypal, enom, and cpanel support for sure. I think Ubersmith looks better, but I am more familiar with Modernbill.

Well both will help you out there. Please keep in mind that my post below is not from any production experience (I have never used either system in a real enviroment). However, I have worked with both systems on different webdesign jobs and it's almost impossible not to poke around. As far as modernbill goes I have used their demo license and had a leased license for two months or so that I did quite a bit of work with.

Ubersmith is really a great system, but from what I saw about it I can't justify the price unless they hold a feature that you really need. From a design standpoint it's incredibly easy to integrate into an existing design as their form builder is wonderful. The admin interface seemed very well laid out and I felt it was quite easy to get around in it. You can play with all this on the demo for yourself of course.

Modernbill is the system I have more expreince with out of the two, and it is a pretty good system in my opinion. I would do some investigation onto the new V5 license system before making a decision and make sure you understand the path your license will taken when version 5 goes release. There will be several levels (nothing is 100% set in stone of course) and the higher levels will be needed if you plan to do any developement work with the system.

The other big difference is the fact that (last time I checked) you can't run Ubersmith on your own server. This can be a good and a bad thing. I wish I could be more help, but with the requirements you listed it really comes down to which one you like best. They both have demos (which I'm sure you know about), but if you don't they're a great tool to help in your decision.

Good luck ;)

Well actually, Ubersmith lite is only around 9 dollers, and you can run it own your own server now.

Thanks for the heads up ;) Been a while since I really looked at their offerings.