I initially used grey ink wash for areas of halftone (inspired by manga but not willing to mess with screentones). Because ink wash is such a pain (it dries almost immediately, and you can't fix it afterwards), I tried doing grey halftones in watercolor. But both Ivory Black and Payne's Gray are a little lifeless on their own, so I tried mixing a "chromatic black" by combining blues, reds, and browns. I accidentally mixed a bluish-purple color, and absolutely fell in love with it. I really like how subtle it can be, and I'm still playing around with a perfect combo, but I think for me it beats gray halftones 10/10.
