Well, a Dragonborn Druid is pretty much the opposite of optimized, that's for sure.
Let's see...
The SCAG subclasses are pretty rare from what I see around here. Other than that...
Barbarians other than Totem.
Bards in general.
Clerics other than Life, Light, and Tempest.
Land Circle Druids.
Fighters are pretty well represented.
Elemental Monks.
Devotion Paladins.
Thief Rogues.
BM Ranger (though there is one guy, every season)
Wild Sorcerers.
Non-fiend Warlocks.
Wizards that aren't evokers, abjurers, or diviners.
Races:
EEPC races are rare. Never seen a Duergar. Only seen a couple drow.
Half Orcs, Gnomes, Dragonborn are all pretty rare. Non-variant humans. High Elves aren't common, but they aren't rare, either.