Baghdad is my favourite map because it normally ends in a draw. Most maps where one team attacks and the other defends is easier to win as a defending player. On Baghdad, both teams are attacking and defending so regardless of your team, the map is more balanced and you can choose to push and be aggressive or defend and be passive.
Haditha and Almaden are very close seconds though. The others I am not overly big on.
Almaden! Its a great map. But I don't know why so many marines still going trough the mosque and dying in the mosque but never push up by the right side buldings. :/