Best Terrain: Alta, Snowbird, Snowbasin (Arguments can be made for Brighton/Solitude)
If its a weekend I would go to Solitude or Snowbasin.
Alta/Snowbird: speaks for itself. Gnarly terrain to be found everywhere esp if you are willing to hike. (Baldy, Twin Peaks, Castle, Etc.. even an early morning lap on Superior)
Brighton/solitude: Quite mountains.. people generally go to Snowbird/Alta or head out to Park City. Pow days at Solitude cant be beat and Fantasy Ridge offers some great big mountain runs. (though not as big as Alta/Snowbird).
Snowbasin: It was the home of the Olympics mahnnnn. Plus the bathrooms are made of gold. Not to mention its got gnarly cliffs and trees up top and is almost always quiet.
Hope this helps/doesnt piss off too many people haha.
This is the truth. When I lived in Utah I spent a couple of years at Snowbird then a couple at Solitude. Snowbird can defiantly have crowds and many of the crowds are really good skiers so even the harder to access terrain can get skied out really quick. I remember a number of days seeing a crowd of 30 people waiting for ski patrol to drop the rope then the bowl getting skied out in 2 runs. That being said, Snowbird is nuts and literally has more crazy terrain than all of Colorado. The lodge is also an Avalanche Fortress so you know they mean business as soon as you show up. Snowbird is actually about 5 mountains in one with a totally different feel to each area:
Peruvian Gulch: Awesome steep trees and really tight rock and cliff features. There are some really fun big mountain type runs if you hike the Baldy Traverse. Usually when all else is skied out, there are fresh lines here if you get creative.
Cirque Traverse "Tram Spine": There is literally a giant spine that runs under the Tram and its a trip to ski down. This has probably the steepest fall line of the mountain and reminds me of Aspen Highlands alot actually, especially if you follow the spine a while then dump down skiers left to Barry Barry Steep etc. It gets skied out quick but its a good way to start the day.
Gad Valley- One of my favorite areas, its a traverse over numerous rock knolls and as it gets tracked out you can typically keep pushing further and further out to grab some fresh snow. Not a lot of vertical but its some fun open bowls and cornice features.
Gad2 Trees- These are all the tree runs looking at the right side of the map. Pacific Northwest type forest tree skiing for days here. Not quite as steep and can be hard to get back to do laps but whenever things are tracked out you can always find stashes here. I grew up skiing Schweitzer mountain and this area reminds me of there a lot.
Mineral Basin- Snowbird doesnt really have a terrain park. That is because Mineral Basin is literally a big mountain huck fest terrain park. My personal favorite is the run right below the mineral basin express lift down the fall line. Its some rockstar hit after hit after hit to the lift bottom then lap it again. Some of my favorite days skiing in my life have been lapping Mineral Basin express. You can also traverse over Skiers right to the Flora Cliffs area but you lose a lot of elevation IMO but its good for when other areas are skied out. Its also fun to bomb the cat walk and throw yourself off the cornice into the open bowl.
Solitude is a really fun mountain in its own right and its by far more quiet than Snowbird with barely any lift lines. The terrain is not even close to Snowbird but there is enough to be enjoyable. The lifts are kind of wonky at Solitude for Mineral basin so you really cant throw down laps. That being said, if you find a good rhythm you can have a good time. IE, Traverse over and find a good line at Mineral Basin, grab the Honeycomb return then traverse over to PowderHorn lift, bomb the steep narrows of Milk Run then grab Summit back up to hit Mineral again. The runs down the Summit trail are pretty fun with some cool little cliff lines and chutes you can hike to as well. Honestly though, if you are putting in 40 days a year you will probably get bored here.
Just my .02