Hello.
My vote is for the now discontinued external iSight.
This thing is a work of art as well as a perfect functioning webcam.
Here's the details:
It has only a 1.3 MP sensor, but it's a camera grade 1/4" CCD instead of the vastly inferior (and cheaper) CMOS sensor used in virtually every other webcam. (including high-end ones such as the Optia) Also, it is an ACTUAL 1.3MP instead of the common "Effective" or "Interpolated" MP rating.
The optics appear to be GLASS camera-grade pieces. Totally unlike my previous eyeball toy webcams plastic lenses (one cheap, one premium).
The autofocus and image processing are all done onboard and require no software to operate. Most PC compatible webcams run the AF and processing in software. This is something to watch out for when buying a webcam for use with a Mac. (or any system running OSX)
It's got a totally cool on/off switch with a built-in and highly visible white privacy shutter to let you know when it's turned off. The only thing that's remotely comparable are the webcams with a much cruder sliding door cover/switch.
It's a Firewire interface. Firewire carries its own dedicated hardware while USB tends to delegate some function to software. This can result in smoother operation which is probably why Apple chose FW instead of USB.
It has a premium dual-element noise-suppressing microphone. Again, it's done in the hardware and doesn't require additional software processing.
It's (mostly) METAL. It has an excellent tilt/swivel thing. it looks cool. Nobody has made a Webcam before or since that has the whole look and feel thing down like the iSight.
The ONLY problem:
It works entirely TOO WELL! AAARRRGGGGHHHH! I look like THAT?

Now I gotta do my hair and powder my nose just to chat!
Can't they give me a "Logitech/Creative/Microsoft emulation" mode so as to make my face an indistinct blur?
Requires 15 minutes prep time to chat,
Keri
Sample picture: