Personally I use tailoring and engineering, partially because I've had both since vanilla, but PvP wise I think they bring something a little more interesting that just extra stats.
Tailoring:
Lightweave embroidery (Intellect proc):
http://www.wowhead.com/spell=125481And for access to leg enchants at any time free of cost, as well as higher tier bags and craft-able gear.
Engineering:
Incendiary Fireworks Launcher (I bind this to SW:D to secure kills) Permanently attaches a mounted fireworks launcher to your gloves, allowing a skilled engineer to deal Fire damage over 3 sec to an enemy at long range. The launcher can only be fired once every 45 sec.
Synapse Springs: Permanently attaches synapse springs to your gloves, allowing you to increase your highest primary statistic by 1920 for 10 sec. The gloves can be activated every minute.
Goblin Glider: Permanently attaches a specialized folding assembly to a cloak, allowing you to deploy a goblin glider and fall slowly for 30 sec. The glider has some initial thrust and allows you to turn while falling.
Aside from that the convenience of having 4 varying teleport items, access to repair bot and mail box is too good to pass up.