A good build could be a Sorcerer. Sorcerers have powerful spellcasting abilities from the start. Their innate magic allows for flexible combat and interaction in the story. For example, being able to quickly cast fire spells to deal with groups of enemies or charm spells to influence NPCs during important story events.
A popular 'Baldur's Gate 3 Fanfic' is 'The Shadow of the Absolute'. This fanfic takes the main plot of the game and twists it in an interesting way. It adds new elements to the story, like a hidden cult that has been influencing events all along. It's full of action and mystery.
The Bard class can be great for the story in Baldur's Gate 3. Bards are charismatic and can use their performance skills to influence NPCs. They also have a wide range of spells that can be useful in different situations throughout the story, like charm person which can help in getting information or avoiding combat in some cases.
I'd say the Drow can be a good race for the story too. Drow come from a matriarchal and rather cut - throat society underground. Their presence on the surface in Baldur's Gate 3 can lead to all kinds of interesting story developments. They have to deal with the prejudices of the surface - dwellers while also having their own internal struggles related to their drow heritage, which can make for a very immersive story experience.
One of the best companion stories is Astarion's. His journey from a vampire spawn with a dark past to potentially finding a new path is really engaging. He has complex relationships with other characters and his personal growth throughout the game is fascinating.
The Paladin class is also excellent for the story. Paladins are knights in shining armor, literally. They are bound by a strict code of honor. This code often leads them into moral dilemmas and complex story situations in Baldur's Gate 3. Their combat prowess combined with their sense of justice makes them a force to be reckoned with and adds depth to the story as they strive to uphold their values.
Shadowheart's story is also top - notch. Her past as a Sharran, her hidden memories, and her gradual discovery of her true self as she travels with the party are really engaging. There are moral choices along the way that shape her character and her relationship with the other companions and the player.
The Githyanki origin story is great too. You are part of this warrior race with a rich history and culture. It gives you a different perspective on the game world. You have unique abilities and interactions based on your Githyanki heritage. For example, your connection to Vlaakith and the whole Githyanki society can lead to some interesting storylines and interactions with other characters who may be in awe or fear of your race.
The Githyanki can be a great choice for the story. Their backstory is deeply intertwined with the lore of the game. They have a long - standing history and their own goals and motives which can lead to some very interesting story arcs.
Shadowheart's story is very captivating as well. She starts as a somewhat mysterious cleric with secrets of her own. Her loyalty to her goddess is tested throughout the game. As she uncovers the truth about her past and her beliefs, she undergoes a significant transformation. Her relationship with the other companions and the main character also evolves in interesting ways.