A snowstorm in winter or something out of season? If it's the latter, early or late?
Definitely in-season. Every time someone brings up sun angle it ruins half the fun.
Wet snow, dry/fluffy snow, or something in between?
Big, wet flakes to start out with and then a rapid change to the highest ratio possible.
Light/calm winds, or windy conditions while it's snowing?
The more exciting the atmosphere the better. Immediate plus points if you can hear the wind howling.
Continuous snow, or do lulls not matter as long as amounts end up as expected?
No lulls. Like sun angle talk or poor ratios, lulls signify wasted potential (Even if these points aren't always detractors, it feels that way in my inner weenie heart).
12" in 12 hours, or 18" occurring over 36 hours?
Don't want to contradict myself, but 18" over 36 hours is just more visually impactful even if the snow falls slower
Bitter temperatures, or just cold enough to stick well during the storm?
Make it bitter cold towards the end. Paralyze the area. Make it feel special.
Storms on holidays/your birthday/some other meaningful day, or are dates irrelevant?
Any time it gives me a day (or two or five) off of work is preferred. Mega bonus points for any snow between the week before Christmas through New Year's. Birthday (Feb 11th) isn't bad either and has a much higher chance of happening of late but I'd actually kill for a snowy holiday season.