I use 2CO and Paypal.

I preffer 2CO but most of my customers use Paypal.

Paypal have never locked my account, but they have put some payments on-hold without any reason. Then after 3-4 weeks, they reverse or release the money and don't tell you what the problem was. If someone claims an unauthorized use of his/her account, Paypal just reverse the payment. No matter if the information you have in your records (IP address, name, phone number, street address) match with Paypal records.