The one with the less fees
Ps: Big ammounts ( 10btc and more..)
Two questions for you on this
1. Are you ready for verification? In that do you have the details they ask for and are you comfortable in releasing them to exchange or third party sites.
2. Are you within the EU region?
If you have the two, then its half solved there several service providers that can do that for you. I know or BonPay but you can do more research on that though. If you are not in EU then I don't see how easy it can be as the option is you sell through peer to peer site which can then be sent to the back account that the Visa card is linked to. Its that simple.