If you really want Enchanting, then Mining is as good as any. Either that or Herbalism make sense.

However, since you're considering mining (a good choice IMHO), why not engineering instead of enchanting? If nothing else, a thrown stick of dnyamite would be worthwhile to pull with when your Avenger's Shield is on cooldown.

Skinning would be my last choice, as its easy to do on an alt.