New Player in need of some class guidance

Hey everyone,

I played a LOT of warmane back in the day (haven't played for 3 or 4 years probably), but I played back in the cataclysm servers. I don't know anything about TBC, but want to play on this patch for whatever reason.

Im deciding what class I want to level as, but don't want to pick a class only to find out it is a bottom tier class that is rarely picked up, or the rotation is 1-2 buttons and will kill me because of how boring it is. Also I would like to stay away from classes that are way oversaturated (ie. everyone plays this one class).

So far I have been deciding between:
Fire Mage
Enh or Ele Shaman, though I would dabble in resto (definitely not main a healer though)
Shadow Priest (probably off spec in heals too)

I really don't know anything about the classes in TBC, and in Cata I mained an enhancement shaman and had a great time on it, pulling out some impressive dps..

Any insight would be greatly appreciated!

TLDR; need to pick my class, don't want to pick something oversaturated, don't want an incredibly stale rotation consisting of 2 buttons, don't know anything about this server or TBC.