I have preferred self-checkouts for over a decade, and I usually avoid grocery stores without them. The user experience is simply superior to traditional checkouts. I can proceed at my own pace, and there is no forced interaction with a random person.

The UIs are also superior to the vast majority of web/mobile software I use, because they rarely change. After a year or two, you just get used to them. And when you visit a foreign country, you often find that they use the same software there as well.