depends on what your looking for...
Alta=( my favorite) super dope terrain, most snow, unbelievable powder shredding, less consistent vert than the bird, opens lots of terrain very quickly after a storm, arguably best back country access, no park, can't shred with your snowboard pals there.
Snowbird=probably over all best/most terrain but kind of crowded in spots, steepest/most consistent vertical, unbelievable powder shredding, but gets tracked our fastest (along with alta too), mediocre park.
Brighton=great powder shredding, lots of snow, really really fun terrain, powder doesn't get tracked nearly as fast as alta/bird, pretty good park, probably best place for good balance between park and pow, but more deusch bag snowboarders than you can shake a stick at.
solitude=great powder, great terrain, less crowded than anywhere else, powder gets tracked less than anywhere else, but hard to find other kids with passes there to shred with, no park.
park city= maybe the best park in the country, but 1/2 as much snow as little or big cottonwood resorts, terrain isn't that awesome at all.
deer valley and the canyons=i would rather spend money on a pass to anywhere else than ski at either resort for free.