I break the judging of a ski are down to four factors, Terrain, Environment (snow plus weather), access to terrain (lifts and layout) and vibe.
The vibe of a ski area is one of the most important and often overlooked aspects of mountain quality. If you took Jay Peak and turned management of it over to the Stratton guys or whomever would shut down the Glades and groom everything, it would completely change the mountain. Jay is great because of not only because of the obvious meteorological factors (which often influence vibe), but because it is run well.
If anyone has ever been to Snow Ridge, they understand vibe. This place is tiny, 300 vert, maybe. 20 trails. Crappy lifts, but they get a lot of snow and everyone there is cool. I've never seen so many smiles. Its a skier's hill with a focus on fresh snow and good times.
Hills with good vibe are almost always fun. Pow Mow has good vibe, Loveland has vibe, Burke is on this list. Even Snowbasin and W/B have their own vibe. Vibey mountains I haven't been to, but have heard about the vibe are places like Alta, MRG, Magic, Bohemia, Jackson etc.
DV, Stratton, etc are the anti-vibe hills. Places that could be ok hills if they were run with/inhabited by those with the right attitude. Seeing miserable people skiing can ruin my day just as much as ice. Its about fun.
Snow and terrain are easier to quantify so I'll leave them out of this discussion.
Access to terrain is pretty difficult to break down, but here is what I like. I want to park near a lift/lodge, I don't want to walk a freekin mile to buy a pass and then another 2 miles to the lift. If parkings has to be far a way, frequent open air shuttles (like Sugarbush's tractors pulling a wagon) are a good thing, buses suck in ski gear. I want trails/lifts that are spread out enough to keep crowds down.
I want access to different types of terrain off the same lift. If I want to cruise a groomer in between tree runs, I want to be able to hop right back into the trees the next run. Jay has this nailed, so does Sugarbush.
I want bathrooms near the base, preferably with an outside entrance that doesn't require going in the lodge. taking a leak should not take away from my skiing too much.
So what are my best mountains? East is Jay, Sugarbush a close second. Burke, Gore, Snow Ridge all score high points.
West I'm not as experienced, but I'll go with Loveland, Snowbasin, and Pow Mow. Even though Whistler is a wee bit overbuilt and overpriced, it scores well in my book for being one fun place both on the hill and off. Its got some pretty sick terrain too!!