There are a number of good choices, in a range of prices. Maybe the most useful option isn't a down "jacket" at all, but rather a down sweater. Patagonia's Down Sweater ($200) may have more warmth per ounce than anything on the planet. Perfect for throwing on when out for a walk or for some extra warmth in the mountains, and it layers nicely under hard shells. Weighs 11 ounces, and packs down to the size of an orange.
In down jackets, a classic example is The North Face's Nuptse Down Jacket ($199). It has excellent 700-fill down, a durable nylon shell that's treated for water-repellency, and a moderately long cut for good coverage without much bulk. Weighs 24 ounces. For a little more heft, try Mountain Hardwear's Sub-Zero SL ($280). It adds a hood, and uses Mountain Hardwear's proprietary Conduit waterproof-breathable laminate, so it's really weatherproof. Marmot's Ignition ($285) is nearly identical in specs to the Mountain Hardwear piece.
But really, probably the best all-around down jacket out there is Feathered Friends' Volant. Just a great piece, with super-fluffy 850-fill down, available with a super-breathable eVent shell, reinforced at shoulders and elbows. I have a 20-year-old Volant that is as good as the day I got it. $399 for the removable-hooded eVent version; $339 with the somewhat lesser Nextec Epic fabric.