I would also argue that any store I've been to with a self checkout line tends to have a majority of the use. I find them faster. My wife was hesitant the first few times she used them, now she prefers them as well. I would argue that odds are you & the people in front of you, who often are in a hurry, will be faster than the person who checks out people all day & is suffering from fatigue & boredom. I would also argue that most people in a checkout line want to get out of the checkout line as soon as possible & with no errors.
In my experience, it's hard to judge the popularity these days as there tend to be more self-checkout kiosks than traditional checkout lines that are actually manned.