it does have the world best snowmaking system
Overrated. Heavenly was 4% open at New Year's last season. If I were flying across the country I would be looking for where there was natural snow. It might be worth staying at South Shore if you decide to ski Sierra and Kirkwood.
It's a complex question what makes a great snowmaking system.
1) Acreage of coverage? Doesn't mean as much as how fast can you make snow when the weather cooperates. So I think...
2) Water capacity is perhaps the most important. I suspect some of the eastern leaders like Hunter, Sunday River or Killington may take the honors here. These places open a lot of terrain on 3-4 days of 24-hour snowmaking.
3) Local climate, how often can you use the snowmaking? Heavenly probably has more snowmaking capacity than Mammoth, but Mammoth was 15% open last New Year's because it has a colder and drier climate and could make snow more often than the Tahoe areas.
Who has the best snowmaking in the West? My guess would be Sun Valley, where I was on a press tour of their facility in 2010. http://www.firsttracksonline.com/boards/viewtopic.php?t=8842