Choosing between gem quest rewards

Is there any ranking as to the usefulness or rarity of some of the offered quest rewards? Yes, I know that its possible to just run through the content multiple times and get all of them - but I don't want to do that yet, my furthest char is Act 2 Normal ;)

What considerations should I think of, for e.g. when choosing between Added Lightning Damage and Weapon Elemental Damage for a Templar? Are there general 'rules of thumb' to keep in mind?