The only self-checkout that I don't like is the Costco self-checkout. Interestingly, I don't appear to be in the minority on that. The one at mine always only has a few people at most in line, even if the other checkouts are all stacked up. For some reason, lots of people are bothered by that one who, like me, are fine with the self-checkout at the grocery, big box, etc.
I'm not sure of the why, other than I think because the regular Costco checkout is generally very efficient, anyone with more than a few items (which is most people at Costco) will get through the regular checkout faster.