I feel well qualified to answer this question since I live in Utah, ski the majority of my days on weekends, and have spent a lot of time over the last 8 years or so skiing with my kids. As a bonus, I play with a set of Ping I3s during the golf season.
I think the above advise is good in that the low to upper 90s is probably the current sweet spot for a one ski quiver in Utah. I have a pair of Bonafides (98s) I picked up earlier this year that work really well. In addition to those mentioned by Sierra Jim, some others to consider might be the Nordica Enforcer or Hell and Back, or the Head Rock and Roll (really good deals on this ski right now). These types of skis are slightly biased to 3D snow use and tend to be less fun (but still very competent) on 2D snow than narrower, more piste oriented skis.
If you are going with more than one ski (and most of the people on this forum would suggest this route), you may want to consider a combination of a narrower, carving oriented ski with all mountain capability and a slightly fatter powder ski. This disappointing snow year has reminded a lot of people of the utility of a ski that is more exciting on 2D snow. If you were to combine that with a good, undemanding powder ski (like an S7 or a softer traditionally shaped ski with early rise) I think you would be pretty happy.
If you are going to focus on Alta, the need for a harder snow capabilities is lessened. If you are going to venture outside the Cottonwoods (ie. Park City areas, Snowbasin etc), harder snow capabilities become more important.
Also, you didn't give your weight which, I believe, is pretty important in ski selection. To a 250lb guy a Mantra may ski like a softer ski does fora 150lb guy.