As I said, nothing right now on market measures up to XBMC/Boxee and I'm not saying it lightly.
I had experience with Popcorn hour, Dvico TViX and Dlink clients. All of them had awkward menus, audio/video Codec limitations, networks streaming issues, Limited HD support etc...
Is Boxee is perfect? Not right now is not, and its still a beta product, but it is the solo platform moving amazingly fast in the right direction. With introduction of ION support I decided not to wait anymore and jump on board, and boy - I'm glad I did.
Boxee Box will be based on Nvidia Tegra 2 platform which should have more raw muscle then any of above mentioned devices.
Sorry its getting late here... i'll write some more tommorow