Opinions: Wireless or USB Keyboard?

I'm buying an iMac that doesn't come with keyboard nor mouse. I have an Apple USB keyboard; the one with the numbers keys on the right. Thinking of getting an Apple wireless keyboard: the one as seen on Ebay, "for iPad, iPhone, Mac OS" or terms to that effect. I reckon it's the one that comes with iMacs.

For those with the wireless keyboard: do you wish you had the "extended" USB keyboard? Vice versa?

I just searched through threads here and saw a few where people have problems with pairing and connectivity with bluetooth KBs.

All your thoughts are appreciated.