This poll serves no purpose.
Also, I only agree with a "sad" ending if it is one of multiple choises. No more ME3 please. For me a nice ending is similar to the BG games. Basically you choose to become a god or remain a human. Each choice has its cons, leave ultimate power behind or abandon a life of adventuring with your friends, but the pros are always nice. In summary, it's a "happy" ending that comes at the cost of something and makes you a little bit "sad".