The current best items for a barbarian are the combination of sets and items for the following two builds :
- Whirlwind (Waste - Set 6 Piece + BulīKathos Mighty Set - Weapons)
- Hammer - Barbarian (Immortal Kings - Set 6 Piece + The Gavel of Judgement)
For every set you might consider using the rings Focus and Restraint or Unity and Convention of Elements and as a necklace a Hellfire Amulett, while the Bracers and Waist are different.
The Whirlwind - Build uses Strongarm Bracers and Pride of Cassius, the Hammer - Barbarian - Build uses Immortal Kings Belt and Bracers of the first Men.
There are alot of different builds you can try out like seismic slam or boulder dash rush, but these are the strongest in the current season for a barbarian. You should keep in mind that next season Call of the Earth - Set will be changed, which might be a good new choice.
Hope my post gave you some inspiration or help on choosing the right specc