Apollo or WPF/E or Firefox

Which one would you choose for RIAs-for-Desktop or Occasionally-Connected-Clients (OCC) ?
We are familiar with Apollo, some of us know about Microsoft’s WPF/E platform which is said to be cross-platform. Mozilla Firefox rocks, specially Firefox 2.0, it provides you persistent-storage APIs among other new features.
I am just thinking why would I be using either of these? Meanwhile, if you have any thoughts please share it.
I would posting my opinion in later post.