*Spoilers* Anyone feel joining Emet would have been better

[Lurina]

Yes, absolutely. You can argue that as 'it's because she won', or that it's because we ended up benefiting from it, and yes, neither of those are wrong.

But the main evidence I put forward on this one is that Emet-Selch comes back from the literal dead and says that her plan worked and his wouldn't have. If you want an unbiased, in-universe testimony as to the relative strengths of both plans, that's the best you'll find: that the guy pushing the other plan, when liberated from the shackles of his own life and granted effective omniscience on specifically this subject, directly says that hers was better, even if he's still mad about it.

I keep being told that Emet-Selch always told the truth. So presumably his words have a lot of weight, and in his final moments, he put them on her side.

EDIT: ...Ironically, that does provide an answer for the topic title. We did join Emet, it's just that we weren't the one crossing the floor.

I think people have started to overhype Emet's 'agreement' with Venat in that scene a bit. He says that his plan wouldn't have taken humanity to Ultima Thule. He also says that he still disagrees with Hydaelyn and that he stands by his actions, with quite a bit more emphasis than the former sentiment.

Admitting a plan is effective at accomplishing its ultimate objective isn't the same as endorsement. If someone rounded up everyone with a criminal record in a city and shot them, then you could certainly say that other means wouldn't have been as effective at preventing crime, but I doubt you'd agree with it. Emet would evidently prioritize the survival of the Ancients and trusting some future generation to solve the Final Days problem another way, over a definitive resolution at the total expense of his people.