The ease of adding branches and moving them around. Identifying them by color. Having multiple projects going. That it's a Mac only app and that it can tie into to-do list apps. Plenty of control to make it visually distinctive between branches.

Mindnode is one of the best mind mapping apps that I've ever used. It does exactly what you need and doesn't try to do more. That way it doesn't get in your way and it allows you to just flow with your ideas. The fact that it also creates beautiful mindmaps with ease helps with the user experience. I like the fact that I can easily export the mindmaps into PDFs, PNGs, and even a RTF which allows me to easily and copy paste longer from content that's wrapped up in a node. Additionally, the icloud integration is nice which makes using mindnode on my iPhone or iPad really easy allowing me to be anywhere and use whatever input device I feel most comfortable with at the moment.

I like that you can share your map with friends and colleagues so that you can collaborate on an idea. It's really helpful to be able to see the way someone is thinking through that type of graphic organizer.