It needs to be popular
It needs to have an easy API for integration
It needs to be secure
It needs to handle worldwide transactions
It needs to handle credit cards and debit cards as well as internal funds.
It needs to have mobile version as well
It would be good to have transactions verified by verisign or some other well known SSL company.
I know there are lists online via google but many of those are just dummy lists created by the companies themselves to give them favor. What i want to know is what are people actually using every day in the real world.
Thanks :)