In my opinion, the United Colonies has a great faction story. Their history of expansion and the challenges they face in maintaining order across multiple planets are really interesting. It shows their struggle between growth and the need to protect their citizens from various threats, like pirates and alien life forms.
The side stories about the different factions in Starfield can be really engaging. Each faction has its own goals and values. The Crimson Fleet side story, for instance, lets you experience the life of a space pirate. You get to do jobs for them, deal with their internal politics, and see how they interact with other factions. It's full of action and moral dilemmas.
The vastness of space itself can be an excellent background. With countless stars, nebulae, and uncharted planets, it offers a sense of mystery and limitless possibilities for a story. For example, a story about a group of explorers lost in uncharted space, surrounded by strange celestial phenomena.
In Fallout 4, one of the best companion stories is probably Piper's. She is a journalist with a strong sense of justice. Her story involves uncovering secrets in the Commonwealth and fighting for the truth. Another great one is Nick Valentine's. Being a synth detective, his past is full of mystery and his journey of self - discovery while helping the Sole Survivor is really engaging.
One of the best companion stories is probably that of HK - 47. His story is filled with dark humor and a unique perspective as a droid assassin. He has a lot of great lines and his loyalty to the player character is interesting to explore.
One of the best companion stories is that of Dogmeat. He is a loyal and loving companion from the start. His story is simple yet heartwarming as he's always there by your side, ready to help in combat or just be a furry friend during your exploration in the wasteland.
One of the best FNV (Fallout: New Vegas) companion stories is Boone's. His backstory of being a sniper in the NCR and his tragic past with his wife makes for a very engaging narrative. It adds depth to his character and his actions in the game.
One of the great companion stories is that of Astarion. His journey from being a vampire spawn under Cazador's control to seeking freedom and redemption is really engaging. His past of abuse and his attempts to break free while also dealing with his newfound feelings towards the player character make for a complex and interesting story.
Shadowheart also has an amazing story. She's a cleric with a mysterious past tied to her goddess. As you progress through the game, you get to uncover her true self, her doubts, and her growth. Her story is filled with moral dilemmas and self - discovery, which makes it really interesting.