Create Bonfire also has some neat implications, but due to AL rules I can't take both it and Booming Blade.
While I think the duo is fun, I'm not sure I'd call a vhuman polearm master or sentinel moon druid "against the grain"
^^ this. You posted two extremely popular builds.
My Cleric/Sorc was unconventional about 6 months ago, now he's super popular.
My AL character has this theme. I didn't grab all of the cantrips, but I'm trying to cherry-pick the good ones. I'm still leveling, but at Fighter 3/Warlock 5 I'll have:
- Thaumaturgy (from race)
- Eldritch Blast (Warlock 1)
- Sword Burst (Warlock 1)
- Guidance (Book of Ancient Secrets)
- Shillelagh (Book of Ancient Secrets)
- Thorn Whip (Book of Ancient Secrets)
- Minor Illusion (Warlock 4)
- Booming Blade (from Eldritch Knight)
- Mage Hand (from Eldritch Knight)
The basic premise is to get 20 AC from Medium Armor, Shield and Defensive style, and only need to pump one stat (Charisma).
Booming Blade + Shillelagh + War Caster is a pretty sick combo, and Booming Blade is awesome for EKs. But it feels like a lot of investment given that I can Thorn Whip for my OAs. I might swap those two, but what for? Acid Splash or Vicious Mockery and either Friends, Mending or Prestidigitation, maybe. Create Bonfire also has some neat implications, but due to AL rules I can't take both it and Booming Blade.
If I had to guess what the next FotM would be, I'd guess Rogue + Booming Blade combos, doubling up on cantrip damage and sneak attack, while not losing out on extra attacks like most other weapon classes do.
I like to play a Rogue. As a tank. With a whip.
Sure it needs a few levels of barbarian for protection but it works.

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.