I'd pick the most logical choice.

Procreation.

Would you let your daughter die:

Poll: 14 YES

Nice people.

A few things.

1. She wasn't his daughter. She was his assignment.

2. Humanity was at risk. The needs of the many outweigh the needs of the few. Don't you Star Trek?

3. He had to lie to her. If his actions were noble, he could let her decide.

4. In saving Ellie, Joel killed several people. Doctors who were just doing their job. Who made the decision to do what was best for humanity. Joel killed them without hesitation.

Would I sacrifice my adopted daughter? I have a real daughter and, for the greater good, I'd sacrifice myself for them. If she grew up and joined the military, I'd respect her wishes and I'd understand why she would be willing to risk it all. I understand that Joel lost his real daughter at the beginning of the game and maybe he saw Ellie as someone who could fill the void but, in the end, he was selfish. He didn't even give "his child" an option.

It is an eternal question. Variations of it appearing in many religious texts. Would you sacrifice an innocent life to save the rest. Am not sure.

Edit: Am glad i didn't have to make the decision in the game. 

Hell to the nah, I dont even like ellie as a character to begin with. She's not even worth me capitalizing the first letter of her name.

If only they were smarter they'd clone Ellie.

Wait how do they build off of The Last of Us 1 for those players who chose the vaccine over Ellie. She is the main character in part 2.

I think Joel would have saved her because of their bond and she reminds him of his dead daughter.
Personally, I would have sacrificed her life for a cure if there wasn't any chance of sparing her.

The vaccine is al but guaranteed if you collect al the audio files: There is one that states that there have been a dozen of trials to extract a vaccine from someone who was immune. They all failed and there is no guarantee that extracting tissue from Ellie would. What is sure is that it will kill her. So the options boll down to sacrafice a Child for a small chance of extracting a cure and an even smaller chance to succesfully spread it a cross the country. Just imagine the monopolyposition in a world as scattered as the last of US if someone had a cure. No way that would get distributed fairly. Or to save a Child against her own wishes and believes. I would change the latter.

1. True but you can still care an awful lot about that if she is pretty much one of the few people which doesn't want to murder you for recources. 

2. Is humanity really worth saving though. 

3. Do you think a 14 year old Child is capable  enough to make such a decission and understand the impact of such a decission. Also Firefly never mentioned the failed trials to extract a cure from tissue from immune persons. Neither did tel the truth in that regard. 

 4. Technically speaking you did kill them. Since you could get what you want without killing them.