After using a few different merchant companies over the last so many years, we use Intuit now directly within quickbooks. They offer next day funding now with CC or bank transfers(10$ max fee any amount!)) and their rates are about the same as everyone else.
The convenience did to for us, as we can send an invoice with a direct payment request and never have to see the clients card or bank info. We also offer a discount rate for anything but plastic to cover the price of the fees.