Chicken: mild, versatile, can be cooked a million different ways.
Duck: the King of Poultry.
Turkey: Thanksgiving necessity, but great year-round.
Goose, pheasant, quail: not always commercially available but excellent birds. Tastes better when you catch/kill them yourself IMHO.
Turducken: why choose when you can put them together?
Other: emu, ostrich, pigeon, others.