I have not been very lucky yet so my best ring is a RORG. I've been using 3 piece Ik set with 5 pieces of waste. I have a non ancient 3700 dps Ik BB and i have 2 non ancient weapons at about 2360 dps each (no as).
If you can, try them both out, although I would contend that BK/Wastes works much better when you have Obsidian Ring of Zodiac cubed. If you don't have much/any cdr on any of your gear, you'll probably find better results out of IK/Wastes. Personally I'm running BK/Wastes despite having crap for cdr because I used my only gift on an ancient BK weapon (I have an ancient IK BB, but it rolled fairly crappy damage wise).