I've tested a lot of clothing over the years so it feels wrong to declare the Outdoor Research Trailbreaker the best backcountry ski jacket on the planet, but it's true.
I've been skiing in this jacket for two months now and I have yet to discover a downside. A medium fits me perfectly. I'm normally between a small and medium; smalls tend to be too tight and I have a tendency to swim in a medium. Too big is ok for the resort but not for the backcountry. When you're living in your jacket on the uphill, it has to fit perfectly.
The Trailbreaker Jacket uses OR's Standard fit: not form fitting so you have some wiggle room while you're swinging your arms, but also not baggy so the elements stay out. The waist is perfect: not too tight and long enough to help thwart the draft. The sleeves are also just right, giving me some room to fully extend my arms and loose enough to fit over the largest gloves.
The hood could stand to be larger so it works better with ski helmets which tend to be larger than climbing helmets.
All in all, the Trailbreaker Jacket is now my go-to for the backcountry, no matter the conditions.
Outdoor Research Trailbreaker Jacket
Links
Outdoor Research Trailbreaker Jacket: http://goo.gl/CV9aJK
More gear reviews: http://goo.gl/0x4zz