In terms of a desktop look/feel the best of that bunch has to be ExtJS. In terms of the UI it really is leaps ahead of the rest. Of course there are licensing issues but they have their FLOSS exceptions and if you intend to make money from the project then a commercial license isn't exactly going to break the bank.
Other Very Rich Framework worth looking at (all have their good and bad points),
- Bindows
- Tibco General Interface
- vegUI
- Echo
