Best and most affordable are in no way synonymous. Additionally, make sure to research the jacket you are looking at no matter the brand. There’s a huge variety of jackets and many do not have any insulation despite them being extremely expensive.

Best available, I would put companies like Arcteryx, Patagonia, Marmot, Mammut, Western Mountaineering, and a few others, but all of these are at the top end of price. Additional high end brands would include Dakine, Mountain Hardwear, Black Diamond, Eider, Spyder, etc.

For value, REI, Columbia, Sierra Designs, and North Face would be my picks, but their really good jackets can still be expensive. Eddie bauer has recently greatly improved their outdoor gear. They often have website sales up to 50% off. Just keep an eye on the website. If there isn’t a sale going on, just watch and wait, 30% off coupons are very common. I wouldn’t buy anything from them without getting at least 30% off the retail/MSRP.

Budget wise, watch ebay for lightly used or NWOT jackets, make sure you know your size before going any route that doesn’t allow returns. Sites like gear trade allow people and some companies to sell new or used gear, often at a huge discount. REI has a discount part of their website called the garage (it used to be called the outlet). Lastly, watch for sales on other outdoor websites like campsaver, moose jaw, http://www.geartrade.com/, rei, there’s probably a number of other good ones.