While this is very much subjective and varies from player to player, here is a comprehensive list of the pros and cons of each joinable faction, in Fallout 4. The question that every player will find themselves asking is 'Which faction is the best?'.
Fallout 4 offers four key factions that can be joined, each with their own quests, items, story, characters, and experiences. From the wikia for Semper Invicta, the walkthrough states: After the discussion, Danse asks the Sole Survivor to help both Rhys and Haylen doing their respective job. There is no way to finish Semper Invicta without becoming a member of the Brotherhood of Steel. Like many RPG titles before it, Fallout 4 offers a plethora of crazy things to indulge in, as well as huge amounts of story options, multiple quest lines and the most commonly discussed of all, various factions to join. Yes, you will need to join the Brotherhood of Steel to complete this quest. This standard of quality can be seen in the 2015 release, Fallout 4. From its humble roots in turn-based strategy on PC, to its modern-day status as a household name, Fallout boasts a quality that very few can deny. The Fallout series has long established itself as one of gaming's powerhouse franchises, and alongside The Elder Scrolls, sits proudly as one of Bethesda's greatest accomplishments.