The best potatoes for chips are older potatoes. Never use new ones. The reason is as they age some of the starch turns to a sugar, thus they brown up better. New ones are hard to get brown and tasty.

Green Mountains are a really dry potatoes. Some of the red variety are quite a bit moister. Another good one is a Sebago.

As to grades, traditionally, the bigger ones were considerd seconds...Table Potatoes were considered the mid sized rounder ones....those that fit neatly in your hand.

Beware of green (sunburned) potatoes....as this is caused by exposure to sunlight or inside light. They contain a nasty toxin that cant be cooked away. It's best to buy potatoes in paper bags....as clear plastic ones (or those exposed to light) allow more of this condition tp occur....especially when stored directly under fluorescent lighting.