PersonalBrain, FreeMind, MindManager - any recommends?

[electronixtar]

I am going to try out few brainstorm software. Main features I need

1. Handling concept loops. I like concept trees, but loops are much more universal.
2. Maybe some Shortest-Path-First algorithm with animation to optimize your thoughts?
3. Maybe 3D graphics showing complex connections?
4. Cross platform(Mobile/Windows/Linux/Mac), multi-people real-time collabrative brainstorming, open save format for import/export

So, is there anything like this?