a four winds poser

Take a look at the above set of mahjong tiles (click to enlarge).

Let's say you're the dealer (莊家), so you already have one double (台) from the flower (一花). But as a result of that, a four-double 平胡 is no longer possible.

Question time: You've just drawn your tile, and you have to discard one from the 14 tiles you hold. Which tile would you discard, and why?