I care MUCH more about the characters (including my PC) than the world. In real life of course you would prioritize the safety of the earth over the safety of one person or a small group but in games it's that small group we come to intimately know and care for. Being forced into a sacrifice like in ME3 is not satisfying to me on any level. What have I gained from it? It doesn't make me happy, it doesn't make sense, it doesn't inspire me, it frustrated me, and has made it so that I can't play ME1 or 2 again even though I loved them. What's the point?
I like both happy and tragic endings but they have to be well done, fit, and make sense. It would have been retarded if in the end of let's say The Walking Dead season 1 (game) Lee finds Clementine not in a hotel kidnapped by some guy, but in a candy factory free from zombies and they discover that the cure for zombie-ism is watermelon candy so they cure everyone and everyone lives happily ever after. That would be utterly retarded. It would make no sense and not match the tone of the rest of the game/series/comic. The ME3 ending was retarded, extreme, and unfitting in the other direction. You take a series who's tone is similar to that of Star Wars or Firefly and who's theme is coming together and setting aside differences to overcome adversity and give it a random, hopeless, nonsensical, and poorly thought out ending ripped off from Gurren Lagan and Deus Ex: Human Revolution and of course a lot of people aren't going to like it.
I want a range of endings (even if it's only 2 or 3) from happy where everyone or most people live to tragic. I feel like forcing a tragic/sacrifice ending in a game that's about choice, roleplaying, and making YOUR character is not a good idea. Sacrifice means nothing if it's not a choice. Having the choice to get yourself out alive makes the choice to sacrifice yourself actually mean something.