Okay, cool, and as always, thanks for the detailed reply. <3
Yeah, I was trying to figure out what kind of uptime she could expect from Killing Spree based on how many mobs she was grinding with WW. It didn't even occur to me to add DoT in to the mix, so thanks for that. Would stuff like Pox Faulds and Thunderfury cool it off as well?
Well, this isn't for right now anyway. lol We don't play a lot, so we're really at the mercy of RNG. I discovered the IK set the other day, so I'd been toying with what she might be able to do with her freed slot if she didn't need her triple-DfA for fury generation any more. Of course, she may never find a single IK piece, much less three or more. I think she has like 4% CDR right now.
As Zenax said, it'll mostly depend on your build. Some stuff is "always" useful, like crit chance, but other stuff is kind of situational. Depending on the skills you've chosen, you may benefit more from resource cost reduction, or cooldown reduction may be better for you instead. If your skills give you a lot of resists, you may want to keep an eye out for Armor++ on your gear. You want gear that accentuates the strengths of your skills, while also balancing their deficiencies.
There are like 8 difficulty levels above the one you're playing. I'm sure you can find one that suits you.