Pretty much any American macro lager, including Busch, Bud, Miller, Natural, etc. Unfortunately this stuff dominates the American beer market, giving the many finer brews also called 'beer' a bad name.
Pabst Blue Ribbon, Rolling Rock, and Coors are two generally recognized exceptions, each having a devoted following of discerning tasters despite their budget pricing. Keystone Light also has a devoted fanbase.
Sierra Nevada is terrible excellent. Try the "Pale Ale", you won't regret it.