Summary
Fallout 4’s main questline is one of its biggest strengths. It’s well told and has great pacing while remaining compelling and fun to experience. Like its predecessors, the title has multiple endings available that require different approaches to the obstacles in the story to obtain, some of which are debatably better endings than others.
Each of the game’s major factions has an ending in line with their overarching goals and morals. The Sole Survivor is able to pick any of these questlines to follow through with, provided they meet the criteria for beginning the final mission.

The Railroad is a secretive organization whose goal is to directly oppose the Institute and Brotherhood of Steel by freeing and rehabilitating their enemies' synth creations. Found through a secretive pathway, the Railroad will take you on espionage and sabotage missions against the Institute. It’s like a spy movie almost and hasa fan-favorite companion, a synth named Deacon.
During the Railroad ending, the Institute’s nuclear reactor at the heart of their base is destroyed, effectively ending the operations of the evil entity. The Brotherhood of Steel also becomes permanently hostile since they believe synths are dangerous and want to eradicate the robotic beings. This ending has the destruction of both the Institute and Brotherhood of Steel. In the aftermath, the Railroad has agents that now patrol the Commonwealth and have flags hanging in Diamond City.

The tone of this ending earns it last place simply due to the fact that the Railroad simply doesn’t act in a way that feels impactful to the Commonwealth. After they gain power, they aren’t in a position to wield it effectively due to their small numbers and less than optimal arsenal.
3The Institute Ending
Should you desire to play as a servant of the Commonwealth’s big bad boogeyman, there’s a sinister ending involving the Institute. To start the Institute questline, you must progress any of the other factions' quests to the point of discovering the location of their facility. After that, you’ll be able to meet with the head of the Institute and begin undertaking missions for them. It’s an exciting series of quests, since you get to be a villain rather than being forced to be a hero.
There’s plenty of combat, exp, and loot to be had during the quests you undertake for Father. At the end of the questline, the Railroad and Brotherhood of Steel are both eradicated and the Institute takes on a more direct approach to ruling the Commonwealth. They no longer hide synths and have regular patrols roaming the map while Diamond City now sports their flag, and Piper’s own newspaper now publishes pro-Institute propaganda. Interestingly enough, the Institute can be allied with the Minutemen despite the former’s evil nature.

The Institute ending simply doesn’t keep you invested, and it never really felt like there was any depth to it. There aren’t any super fun characters involved, and the whole thing is just sad to say the least. The Institute ending also never really felt like an accomplishment, since they were already in power before the game even began.
2The Brotherhood Of Steel Ending
Do you wish for the Brotherhood to be in a position of power? You’re in luck. There’s an ending where the B.O.S becomes the dominant force in the Commonwealth, beating out the other factions. The questline is available very early on, since you’ll be on your way to Diamond City when you first encounter members of the Brotherhood. From there, you’ll need to progress the main quest further before being able to take on more missions for the Brotherhood.
The B.O.S has one of the best questlines available with a very surprising plot twist that is both captivating and saddening. In the end, the Railroad and Institute are both destroyed, and the Commonwealth is now under the thumb of the Power Armor fanatics. This ending can also end in the destruction of the B.O.S if you become hostile towards them and ask the Minutemen for help taking them down.

This ending feels great to achieve simply due to the Brotherhood of Steel being the newest of the major players in the Commonwealth, making their victory feel more impactful. The characters involved were easy to like and fun to interact with, like Paladin Danse. Despite being very duty-driven, he opens up after a long while and eventually is a great companion to have.
1The Minutemen Ending
The Minutemen ending is the epitome of ‘the good guys win.’ This is the easiest ending to achieve, since you meet Preston Garvey around 30 minutes into the game along withour favorite canine friend.It’s relatively simple compared to the other questlines and even features a fortress to take over as a new headquarters for the organization.
Upon liberating the fort from Mirelurks, Preston Garvey will remark that it’s time to take the fight to the Institute menace. This begins the quest ‘The Nuclear Option.’ The quest follows many of the same objectives as all the other quests where robotic annihilation is the name of the game. Teleport in, kill synths, decide the fate of one particular synth, and blow up the reactor.
This is also the only ending where you have the potential to maintain civility between the Minutemen, the Railroad and the Brotherhood of Steel. Of course, should you desire to ruin that peace, you can blow up the Prydwen with the Minutemen and eradicate the Brotherhood.
This is easily the most satisfying ending due to Preston’s pure intentions of just making the Commonwealth a safer place for all. The Minutemen don’t have an army of Synths or a giant zeppelin full of soldiers. They’re simply people with a common idea who banded together, much like groups we see in real life. This connection between our world and the world of Fallout makes the ending feel extremely well-fought and worth every stimpak used to save a settlement.