snow tires better shorter or wider

Yes they do. Wider surface area allows for more floation but you really want the tires to go strait to the ground so a thinner tire is better. A lot depends on the treds ability to displace the snow but as a rule of thumb... thinner tires is better for snow.
Kevin
 
215/60-16 sounds like a decent size if the rim is 7" or narrower.
When running a snow tire you want a narrow tire to avoid flotation and increase contact pressure.
Nothing sticks to snow as good as... snow... keep that in mind when looking at tread patterns.
Bridgestone was the first to use snow in the tread with the Blizzacks, and now Michelin, Goodyear BFGoodrich etc., all make a similar tire... and they plain work.
 
Thin narrow tires have more weight on them because of the smaller contact patch touching the ground. Less area means more PSI between the tire and the road. It's why wide tires are easier to hydroplane. Less weight plus more area for the tire to "surf" on

Also, the narrow tire cuts through the snow/water better.