For plotting one square at a time by hand, I use CorelDRAW, because I bought it in college and that's what I learned to use for basically everything. (And it's already paid for....big deciding factor there.) I made my own templates for blank charts, picked symbols out of Windings, and I can basically design a 5" x 7" pattern from scratch in a day, from concept to PDF file.
For converting photos to charts I've tried CStitch, which felt a bit clunky and inflexible, and Ryijy Stitch Designer, which was easier for manipulating color range, but still didn't blow me away. TBH I don't convert a lot of photos anyway, but if I need a third piece of software to test, I might try Haftix next. I stumbled across it while following a link to the world's biggest cross stitch:
http://www.my-cross-stitch-software.com/battle_of_grunwald/I see several people liked KG, then and now, so I might take a look at that too, but I'm so comfy with Corel that it would have to be pretty awesome to make me switch entirely. :)