You'll want +3 damage.
I tested a bunch of different enchant set ups and ever since ele got nerfed, its really not great, even dual wielding for ranged dot poke. Dual ele obviously outpaces 2hander with ele in that regard but thats it.
It takes maintaining a perfect, uninterrupted dot rotation on at least 4 targets (and that includes getting bomb on those four targets) for ele force to even be in range of +3 damage and +10 agi. Not a situation you're ever going to find yourself in.
+3 weapon damage and +10 agi are pretty similar DPS. I did a bunch of different rotations and such just trying to build a large sample size to say which one is best, but its really a coin flip. But weapon damage gets the nod from me because the +10 agi gets more of its output by increasing your pets damage. Since pets cant be on multiple targets and you often use them for slows as much as damage, +3 weapon damage is choice.
All that said, my hunter has +10 agi because I got a sick staff and didnt have game time to put weapon damage on it. And she does just fine.
Edit: Dammit, Ohti always in here with the quicker and more concise answer.