I've been thinking about this in terms of Baldur's Gate III when it hits full release and we get to make a 4 PC party. I want to cover:
Face, Scout, Sage and Brute archetypes.
Divine, Nature, Arcane and non-magical.
2(+) Melee, 2(+) Ranged.
Someone that can use big weapons, bows, finesse weapons and shields.
Someone in heavy armor, someone in light armor, someone in medium armor.
This limits me. If I am going to have a high intelligence sage with a lot of intelligence proficiencies and maxed intelligence, I will need either a wizard or artificer (or maybe a bard). Wizard makes the most sense. That is generally going to be Ranged and Arcane being covered, and a Half-elf to get me enough proficiencies. The school will be determined by campaign Setting. Intelligence Skills Covered.
For a scout, I like a Ranger Archer. I want to have a lot of skills (thieves tools, survival, perception, insight, stealth, athletics, investigation) to allow me to be sneaky, perceptive and effective at getting to places. I'll add a touch of rogue, fighter, sorcerer and cleric to it over time. Glasya Tiefling. She can use bows and finesse weapons.
Then we need two front line types, one divine and one able to function without magic. For the Brute, I was someone with a high Strength for athletics checks. I combine the Face and Brute rolls into a Warlock Hexblade with Athletics, Deception, Insight, Persuasion and Intimidation. 16 Strength and Charisma to start, meaning we'll be limited on Dex and Constitution, while being foolish and unintelligent - which explains why they are a Hexblade. Variant human allows us to pick up a feat - which will be used for Great Weapon Master as this will be our big beater in medium armor.
That leaves a need for a Heavy Armor wearing Divine PC with a defensive focus. This could either be a Paladin or a Cleric, and either would be good in this role. I think I'll go with a Multiclass.
Half Elf Wizard (20 levels - School TBD).
Glasya Tiefling Ranger (Gloom Stalker 5, Divine Soul 5, Cleric of Order 1, Assassin 5, Battle Master or Arcane Archer 4).
Variant Human Hexblade (17 levels in Hexblade to start - then 3 in College of Whispers Bard).
Half-elven Vengeance Paladin 6, Forge Cleric 14.