I enjoy boiled Yukon Gold potatoes - sliced with the skin on, mashed up a little with lots of butter. But those are not mashed potatoes.
I do not want lumps or peel in my mashed potatoes. I do not want whipped potatoes. The easiest thing is to rice them - perfectly smooth and very fluffy. I don't peel them before I cook them as the ricer doesn't push the peel thru. I use lots of melted butter and warmed milk or half and half. Sometimes I add creme fraiche. Just a quick stir after the potatoes are riced and they are done.
Potato ricer: