I swap party members in and out a lot, mostly for story reasons, but here is how I built them:

• MC: Ancients Paladin 7/Swords Bard 5 - Polearm Master, Sentinel - Lockdown Tank/Support
• Karlach: Wolf Wildheart Barbarian 8/Thief Rogue 4 - Great Weapon Master, Tavern Brawler - Heavy Weapon Beatdown, Advantage Generator, Skill Monkey - MVP build
• Astarion: Thief Rogue 3/Swords Bard 7 - Sharpshooter - Skill Monkey, Machinegun - MVP build
• Gale: Conjuration Wizard 12 - Utility, Control, Haste-bot
• Lae’zel: Eldritch Knight Fighter 11/Rogue 1 - Tavern Brawler, Sentinel - Gith Dragoon - MVP build
• Shadowheart: Light Cleric 11/Druid 1 - Blaster, Support
• Wyll: Fiend Warlock 6/Vengence Paladin 6 - SMITE
• Halsin: Moon Druid 10/Monk 2 - Wildshape Tank
• Jaheira: Land Druid 12 - Blaster, Control
• Minsc: Gloomstalker Ranger 4/Bear Wildheart Barbarian 8 - Tavern Brawler - Improvised Weapons Control Tank