I've heard alot of bad about myPaySystems, even though I have an account with them and have personally not been through any problems.
I also have had ProPay.... But they charge an arm and a leg for an API, so I used to manually process CC... (weird setup, but I was in before they charged an annual fee an was grandfathered in and still don't pay one)
I now have a merchant account, PayPal, myPaySystems and ProPay...
I try to steer people to either PayPal or through my merchant account.
Finally if you're talking one-time charges (NON-SUBSCRIPTION), then PayPal NO LONGER requires that buyers signup for paypal to buy from you....
This has helped somewhat and probably has quite a few wrenches thrown in once you cross any borders of course...