You know, they're kind of two different types of games. Age of empires is like building a society, while COD is just a first person shooter, so it depends on what you're looking for exactly. They're both really great games, either way.
PICK THE CALL OF DUTY, I KNOW I WOULD. but COD is a console game, and Age of Empires III is a PC game. WTF?
depends on you, if you like action games then call of duty, if you prefer strategic games then probably age of empires.
Well both games have completely different genre. You can't compare them, which is better or which is not. Call of Duty 4 is First Person Shooter game, and honestly, I'm addicted to its multiplayer - I still play it 3 hours daily even after 4 years. I only started playing AoE3 because I loved AoE2, but I don't like it much, don't know why.
You can't compare two games in such different areas. They are both good in their own way but there is no way you can compare them. RTS and FPS don't go together. Stop asking silly questions.