I prefer having the choice to self-checkout. Given a free self-checkout and an empty lane with a cashier, I almost always go for the self-checkout: there is no need to interact with someone who is forced to smile and greet me by corporate policy, and I can arrange the groceries in my bags in the way that I like.

Plus - it always feels better to do things with one's own hands. Since the rise of the self-checkout, going to a grocery store that only has human checkout clerks is starting to feel as uncomfortable as driving to a gas station in New Jersey and being forced to rely on a human attendant.