The best potato for mashing are Yukon Gold potatoes.
Russet Potatoes are also good for mashing.
The Yukon mashed potatoes are good for mashing because they are rich texture and subtle creaminess make them great for all of your mashing needs.
When making homemade mashed potatoes you should choose and use higher starch potatoes like Russets or Yukon Golds for the fluffiest, smoothest and most flavor-packed mash.
Russet varieties mash up light and fluffy, while yellow-fleshed potatoes like Yukon Gold have a naturally buttery flavor and creamy, dense consistency.
Waxy potatoes (like white potatoes and red potatoes) are more prone to gumminess when mashed, as opposed to starchy potatoes (like Yukon Golds and russets).
Choose starchy potatoes or a mixture of waxy and starchy potatoes.
When potatoes are mashed, starch is released.
The more you work the potatoes, the more starch gets released.
When too much starch gets released, the potatoes become gummy, gluey, and unappetizing.
I also suggest using a ricer or food mill for fluffy, lump-free mashed potatoes.