Least played classes at the moment?

[Echelos]

I'd say tempest/windwalker, chaos mage, dark summoner, abysswalker, and valkyrie/dragoon.

Abyss Walkers are definitely fun so try one and see how you feel for it, also I agree with Miki, Valkyrie's are great so don't leave them out.

[milktoast22]

tempest and windwalker.

lenceas seem unpopular as well even though they are quite strong.

defensio probably least popular though.

also light bringers/abyss walkers.

[Fuse]

CRUSADER people! C-R-U-S-A-D-E-R!