Alternately, get silly - a skeleton bard whose inspiring performance is playing his ribs like a xylophone!

Summoner might be the most unique, as it opens up roleplaying opportunities at the table - potentially giving you two different personalities you can inhabit.

Anger/Devotion Phantom Summoner was really cool to play, as long as you're good with the Occult spellcasting tradition.

I think a cool thing would be to highlight classes that stray the furthest from 5e's base classes - things like Kineticist, Summoner, Thaumaturge or the playtest Necromancer.