The full list of subclasses
Barbarian: Ancestral Guardian, Zealot, Storm Herald
Bard: College of Glamour, College of Whispers, College of Swords
Cleric: Forge, Grave
Druid: Circle of Dreams, Circle of Shepherds
Fighter: Cavalier, Arcane Archer, Samurai
Monk: Kensai, Drunken Master, Sun Soul
Paladin: Conquest, Redemption
Ranger: Horizon Walker, Monster Slayer, Gloom Stalker
Rogue: Inquisitive, Scout, Mastermind, Swashbuckler
Sorceror: Divine Soul, Shadow Magic, Storm Sorcery
Warlock: The Celestial, The Hexblade
Wizard: Warmage
A pretty diverse selection but they can be organized by themes.
Religious: Forge, Grave, Conquest, Redemption, Divine Soul, Zealot, kind of The Celestial.
Feywild: College of Glamour, Circle of Dreams, Circle of Shepherds.
Shadowfell: College of Whispers, Shadow Magic, Gloom Stalker, Grave, Hexblade
Defender: Cavalier, Ancestral Guardian
Horizon Walker could fit in with any planar theme, but because ranger can take fey summoning spells fits with the feywild best.