Just one? It depends what application you are going to use it for. Could you be a little more specific?

I have heard that the Sanyo panels have the highest efficiency ratings than any other panel. my vote is with Sanyo! 

So what would be a good, efficient panel for western Washington (Everett area).  What type do most people use?

i agree with solar boy, efficiency and cost, must be balanced. To be very honest, there are too many companies producing solar panels. Efficiency for mono cell solar panels normally is above 16%(leader in the market at 17.3%). Most companies can guarantee a 25yr life span. What is left is the price and your personal preference.

from what i know, US end users are paying like USD$5/W, but china companies are selling at USD$2/W. Difference? Not much. then why the price difference? labor cost, and maybe the solar panel has already changed hands many times. But advantage of paying $3 more per watt? More efficient after-sales service due to distance.

There are quiet a few companies out there that make good solar panels.  As a retailer of solar products I did research and found a few places in California, but most great companies are in China.  Currently many retailers are selling the low end stuff because some of the high end companies will only sell their stuff in bulk prices with contracts.  With advances in technology solar panels will be getting cheaper, but when it comes to quality it really depends.  I really like kyocera solar panels from my experiences.

I agree, Kyocera makes a good panel. One thing I like is the higher efficiency which means you can fit more watts on a small roof and less racking. This company should be around long after many of the others fade away. Wholesale Solar uses these panels in their WSS-Select package systems. It is amazing to see how low the prices have dropped.