Pick an equipment slot to upgrade.

[Chesspiece_face]

At the point you are at I would seriously begin looking towards what your end-game plan is going to be. You're at the point where you are going to be spending more and more on minor upgrades and it will become extremely gold and time inefficient to keep plucking away at minor upgrades. Start looking over the auction house and planning out what set pieces you are going to want and what legendaries you are going to be looking to settle on for your final pieces. Prices are going to be in fluctuation in the next month or so with the higher influx of items coming next patch. It's also probably going to be easier to build up gold stockpiles to some degree. Start saving gold and looking for deals on those items you choose for your final build.

Some ideas:

Helm - Inna's Radiance
Shoulders - Vile Ward
Chest - Inna's Vast Expanse
Neck - Blackthorne's Duncraig Cross
Gloves - Tasker and Theo
Belt - Hellcat Waistguard
Bracers - Lacuni Prowlers
Ring 1 - Natalya's Reflection
Ring 2 - Skull Grasp? (This would be a no-brainer if the +Elite Damage was going to stay on it.)
Pants - Blackthorne's Jousting Mail
Feet - Natalya's Bloody Footprints