One can presume the preferred option is their preference.

Probably Liberapay. They don't take any fees because they're also funded via donations. The only fees that occur on there are the payment processors (banks, credit card companies, PayPal, etc), and you have to deal with those fees no matter what

My understanding is Ko-Fi which is why it's preferred. As others pointed out, payment processors take out some fees for card usage, and my understanding is that Ko-Fi takes the least. That said, we have options because most of them aren't too bad, and all donations help :)