I think they are both great options.
Corvette from CCBill is always around if you have a question.
Rand from Paycom is also always there when you need him.
Netbilling is a good solution as well. Having your own merchant account has many benefits and Mitch is a great person to get you setup.
CCBill, Paycom, and Netbilling have been around for a long time. I wouldn't know which one to choose.
If you are looking for high-risk high-volume processing options you can send me a short e-mail to my hotmail account
[email protected]. I can make some connections from there on.