What is the highest quality camcorders?

It all depends on several factors: budget, image quality, sound quality, user interaction, computer connectivity, etc.)

Overall I would say there are three main competitors: Canon, Panasonic and Sony (in alphabetical order to avoid further discussion).

In my own experience (18 years in the professional video production arena), Canon is really good with optics (plus they share several features with Sony, like optical stabilization and video formats), Panasonic is good (generally) with open protocols and Sony has what we call in the business "the Sony Color" (which basically means the color rendition is extremely pleasant).

But again, there are several factors to really get to a definitive answer -- so the best way to answer everybody is to ask yourself: How you plan to use your camcorder? -- depending on your needs (and means) will depend which camcorder has the best video quality.

You can't go wrong by choosing a model from any of the Big Three (preferably HD, obviously).