best device for video conferencing

Logitech HD Pro Webcam C920

http://www.logitech.com/en-us/product/hd-pro-webcam-c920

But....what you mean with "best camera and microphone"? Try to be more specific.....Do you have particular requests or do you simply need a very good HD camera with an excellent audio?

If so, that above camera can feet your needs.....

If you're in a noisy environment, you may want a headset and mic, and the Kingston HyperX Cloud II is excellent, if not very "corporate"
http://www.pcmag.com/article2/0,2817,2476203,00.asp

it is for conference room ...for meeting room ( 12 people )     ............very good HD camera with an excellent audio .....and to zoom and cover all people and all people talk

Skype may not be your best option here.  You're probably going to need external microphones, plus speakers, and a high-quality camera.  We have a Polycom HDX7000 IP based system which has been in use for 2 or 3 years, and gives excellent service.

here somebody mentioned Logitech HD Pro Webcam C920......more better than this .....but not high end like polycom IP