I was going to suggest RealTimeBoard, as well. I’ve tried many mind mapping, illustration and diagram applications, because I use them for a variety of things. RealTimeBoard is great for all kinds of things; I’ve used it for laying down my ideas. Draw.io and Freemind are also great for faster and simpler charts, and easier to integrate into your workflow.
Though you’ve found what you’re looking for, I’d still like to suggest, for you and others, something that wasn’t mentioned. TreeSheets is an open source software, which looks simple, but once you get a hang of it (it’s not as easy to get into as the other applications), it’s actually really nifty and powerful. I love it.