I am a business owner, I started with PayPal, Stripe, Square, ProPay, etc.
Authorize.Net is probably the only credit card processor around with full customer support, 24-7. You speak with real people. You don't speak to a computer or you don't need to send thousand of emails in order to get an answer, you speak with real people/ real customer support 24-7. You don't find this support anywhere else.