So the question are 1) if you wanted the best gear to cover wind and rain, light and durable, what would you buy ?
I don't think there is one perfect piece of rain gear. Durability, waterproofness and breathability are often at odds within a particular jacket. In other words, I don't think you will find any garment that scores a five star rating in all three categories, regardless of price or weight (which are another two important categories).
You might consider buying a variety of gear and matching your trip to your gear. The Northwest climate is rather dry in the summer. There are rainshadows. We get stretches of good, dry (and predictably dry) weather in the summer. In the other seasons, we get really long stretches of bad weather. The weather to the east tends to be drier, but gets more thunder and lightning. In other words, you will probably bring different gear on a three day trip to the Teanaway in August versus a week long trip to Olympic Coast in November. Likewise, I would bring a different jacket if I was hiking on the PCT versus a bushwhacking extravaganza.
As far as particular gear is concerned, I would read the "State of the Market Reports" on Rain gear. Here is a link to the State of the Market Reports: http://www.backpackinglight.com/cgi-bin/backpackinglight/xdpy/sf/Gear/State%20of%20the%20Market%20Reports/index.html
(just search for "rain").
2) If you think it is wrong to try to deal with wind and rain with a single article of outerwear, please explain, and tell me what you would do instead.
A windshirt is redundant. The only reason people bring them is because they tend to more breathable than a rain jacket. This means that they provide for a far more comfortable range of conditions for which a puffy jacket is too much, and a T-Shirt is too little. Whether you want to bring a wind shirt depends a lot on how much discomfort you are willing to endure. You need to provide for the extremes; you need to be prepared for heavy wind and rain. But dealing with the in between weather is not essential.
Fleece breathes really well but is heavy for its weight. When day hiking, I bring fleece on every trip, every condition, rain, wind, sleet or snow. For backpacking, I count every ounce and bring a synthetic puffy. It won't perform as well as fleece if it if is under a rain jacket while under heavy exertion. However, when I've encountered those situations, it has only been for relatively brief periods (a few hours, not all day). In other words, I've never had to travel miles and miles in a hurry while under relentless rain (I've hunkered down or the rain stopped). In that situation, a poncho would be better than a rain jacket. As it is, it performs just fine under those conditions. The jacket loses some warmth, but not as much as down does. I think a synthetic puffy is a great compromise between fleece and down. Of course, if the treated down works well, then it could replace the synthetic puffy.