When it comes to mashed potatoes, you want to look for high-starch potatoes, as they'll yield a lighter, more tender mash. Think of it like a math equation: high-starch potatoes + butter + milk = mashed potato heaven. Russet and Idaho potatoes are like the dynamic duo of the potato world, they're the perfect pair for mashed potatoes.
Now, I know what you're thinking, "What about waxy potatoes like Yukon Golds or Red Bliss?" Well, let me tell you, those guys are like the cool cousins of the potato family, they're great for roasting or boiling, but they're not the best choice for mashed potatoes. Waxy potatoes have a higher moisture content, which can make them gluey and unappetizing when mashed.