I just finished the main quest line, and I'm disappointed and a bit depressed -- and not just because you're in a post-apocalyptic wasteland. It's that no matter which faction you back, if you want to finish the main quest line, you have to commit wholesale murder. I went with the Railroad because, yeah, synths are people, too! And what do I do for the RR? Why, kill synths, of course! They're kinda hypocrites. I've played a lot of Bethesda games over the years, and I don't remember another with such a poor main quest line. Does that seem right to people, or have I just been spoiled by games like The Witcher 3? I still have plenty of exploring and settlement building to do, but I really don't want to do the main quest line again, like -- ever.

Synths are people, you make me laugh. You will now be replaced by a better version of yourself. I've played FO3, NV and this one, I have murdered plenty. No bother to me, someone has to die. NV you had the options to take out multiple factions, didn't lose any sleep. Gotta do what you gotta do to survive this crazy world. Watch out for number 1, but don't step in number 2.

You chose poorly...

The railroad are a bunch of a naive hippies with no real understanding of the damage they're causing to innocent lives with their whole "synths are people too" spiel.

Next playthrough just burn them and don't look back, then side with the real saviors of the wasteland, the Institute.

I think it adds more depth to the story that the RR is questionably worthwhile, that the Institute does evil things but may be the best hope for humanity, that the BOS is run by a deluded egoist while the BOS on the ground are cleaning things up and making the Commonwealth safer. The MM may seem like the obvious good ending, since the others are so unclear, but the MM start out with one guy. Other than good intentions they don't bring much to the table. All of that nuance makes for a better quest, imo. None of them is clearly the right choice and the gameworld is changed in different ways by the choice you make.

- it should have had multiple endings

- faction alliances , peacefull solutions ...who know maybe in a future DLC