Bird 2 is meant to sit on a slight vertical angle, so would be best in a necklace. He's also 2" or 5 cm. long and has a bit of an antique patina. He's very elegant in person.
Bird 4 has a patina that is aging nicely and will get darker as he gets older. Any of these birds can be cleaned up with a ketchup or lemon juice bath and rub, but it would take away some of their character.