I second the Nokian's. They are an all season tire, but perform as well as many winter tires I've driven. Here is an example of how much traction they have:

My wife left a friend's farm near the tail end of a storm. There was about 20-24" of snow. It was blowing and drifting on the 1/4" mile driveway which includes a pretty good hill in the middle. My wife forgot to put the Excursion in 4wd but made it fine. After she left they called her and wanted to tell her they'd never seen anyone drive though snow like she had. They said she was pushing snow the entire way, it was up to the middle of the grille! And she was in 2wd.

So, yeah, you could find better snow tires I'm sure. But I'd say the Nokian Vativa A/T's are great and since they are A/S they'll last much longer. I've driven Michelin/Cooper/Goodyear/BFgoody and non compare.(non snow tires)

The only downside is they are expensive, but i gues you get what you pay for. The shop I get my tires from told me F250s are getting about 60k out of the tires so at least that is decent.