I suggest to try and see the result.
Some customers prefer to have choice, others prefer simplicity.
From technical point of view, credit cards work a little better as users are not redirected to third party page (PayPal) to submit payment, so it looks and feels more transparent in terms of shopping experience.
Accepting credit cards also do not require you to setup any third party account to work properly. PayPal does need a few settings to be setup over at Paypal.com to function correctly.
Personally I would enable credit cards and disable PayPal, but as I suggested before, perhaps it is better to try different options and see what your customers prefer.