So should you buy Mind Manager on Mac or PersonalBrain ? MacWorld has this advice:
While there are plenty of outliners, Getting Things Done, and project management tools for the Mac, PersonalBrain 4.5 gives you a powerful, innovative non-linear capability. Its closest competitor, MindJet’s MindManager 7, has a more Mac-like interface but imposes a great deal more structure on your mind maps.
Personal Brain: Creates intuitive 3-D mind maps; takes a non-linear, context-sensitive approach. Steep learning curve for unfamiliar interface; no way to import existing OPML outlines; expensive.
MindManager: Outline view allows you to easily switch between different organizing principles; many new export formats; easy to move data to and from outline and project-management applications; better printing options. No Microsoft Office integration; maps exported to and from other applications lose special formatting.