Personally, what I look out for is synergies and specializations. I plan out my characters around a specific couple of skills and will focus the entire build around it. I am not a believer of "Jack of all trades".
For Example, my Barbarian is going to be focused on Whirl Wind as a skill. Focusing on having Fury generating to keep Whirl Wind going at all times. (I think the gold rune isn't complete for whirlwind, it will have some reduced cost, but how much yet I think is still unknown.)
I think it is important to figure out what it is you are aiming to do, and then focus your build towards it. After that you can focus your gear towards that class also.