Mage ?

Is it better to go for an intelligence - dexterity, intelligence - air, or intelligence - air - dexterity ?
I can't choose .-.

 

Int and air

 

Intelligence is generally better in the long run of your life

 

Depends on your class really. I'm a mage and I chose the final. Archer and assassin could choose that as well. Warrior... wouldn't have chosen any of these three with warrior.

I like to do something like this:

-Extremely high primary skill point (e.g. 100 in intel, useful for getting mythics and any other items with high requirements in your main skill point, which is intel in your case)
-Medium size secondary skill (e.g. 60 in agility, useful for getting a lot of items, gives a good boost)
-Small minor skill (e.g. 38 on dexterity, gives a small boost and may allow you to get some items)

So I would recommend all three. Make one go up to 100 and split the rest with the other two. Look around for a mythic you would think of getting if you ever have enough money or luck to get one. If you do get one, your play style will conveniently fit a certain one, so you just sell the mythic if it wasn't the one you wanted. Aside from mythics, these high ids allow you to get powerful items like zodiacs, which are a lot less rare than mythics, but are still legendary. Then the next skill point just allows you to get more items and gives a nice boost. The final gives a small boost and may give you items, but the small boost is the main thing.

To look for which elements you may prefer, I'd recommend looking through the item guide for any items you like for all three skills. Then use your favourite ones to make the set of items you want, and you'll have the skill points you're aiming for.