you have 5 different ways to "Tab target" currently.

*0 key on the num pad acts as a "target directly in front of you"
*then you have target nearest to furthest (and its reverse)
*then target nearest enemy
*then target based on previous targets
*and lastly, my favorite, 4 and 6 on the num pad. (Left/right) which cycles through mobs based on what is left/right of the screen.
mixing between 0 and then 4/6, you can usually target what ever mob you want, with a single button press, even if there are 10 mobs on the screen (no mouse needed)

this alone makes me enjoy the targeting in FFXIV, more than any other MMO.