My favorite is the Chintendo Vii.
Also, after I picked up the Chintendo Vii, I can NOT tell which one is my Wii and which one is the Vii. Seriously.
I actually own a Wii knockoff called SwingZone Sports that I got when I was about 5 years old.
I actually couldn't tell the difference between that and a Wii.
Because I was a dumb kid.
(If I can ever get some gameplay footage or screenshots from it, I might upload it.)