A forum member has PM'ed me asking about our impressions.
I thought I will write a summary post about it, so that it is useful for the others as well.
We checked out 6 resorts in total - Snowbowl AZ, BrianHead, Alta, Solitude, Snowbasin and Brighton over two weeks (10 days on the skis total).
Early Dec 2015 was more generous in terms of snow for the southern resorts (Snowbowl AZ, BrianHead). Off-piste was only available in Snowbowl AZ.
When we were leaving SLC (Dec 14, 2015) we had probably the first serious Wasatch winter storm. It snowed 20' overnight at the edge of the mountains (probably more up high). It is a shame that we did not get to ski it.
Few days before it we had a powder night skiing in Brighton and it was super fun. Skiing in solitude during heavy snowfall through the forest passes in Brighton was an experience in itself.
Few comments about the resorts:
Snowbowl AZ - expensive but uncrowded. Well groomed, nice and wide pistes, however basically just two of them. Views are superb. Slow and unsafe lifts (hort my hand in one of them). Best for intermediates.
BrianHead - best value for the money. Views are on par with Snowbowl AZ if not better. Excellent for beginners and early intermediates. Nice and wide pistes with very consistent drop, however relatively short (the base is very high). Main lifts are modern. Friendliest staff.
Alta - I was the only one of our party who enjoyed it (but not Collins part). For our carver it was too crowded and overrun with reckless freeskiers, for our lady skier the blues were uncomfortably steep. Expensive and crowded.
Solitude - basically like BrianHead just a bit more expensive and without the views. Lived up to its name - no crowds. Overall a very cosy and modern resort. The early season pistes are superb albeit somewhat short. Half of it (including all longer blue pistes) was unavailable in early Dec. If I happen to be in SLC again, Solitude is my choice.
Snowbasin - locals were telling us that it was a "hidden gem", but for us it came at the bottom of the six. Crowded and relatively expensive. Felt like a lackluster attempt to imitate Italian or Austrian resorts. Pistes are narrow and inconsistent. There are couple of long pistes (~3 miles), but they do not compare to what is available in the Alps. The over-the-top lodges is the main "highlight".
Brighton - caters to snowboarders (as one local has warned us). I would add schoolkids. The resort itself is unique - pistes scattered in the forest - and enjoyable as long as you are able to avoid reckless snowboarders and ignore the F words, screaming and shouting. This means you have to be early on the mountain or ski at night. Night skiing was a highlight.
All the impressions are of course subjective. I shall mention that it was our first trip away from Italy/Austria where we normally ski.
Our party is also piste-focussed skiers. It appears we ski on a narrower skis than most US skiers (and we brought our own skis).