It's a win win really. Alta has rad terrain and a solid amount of slackcountry access. With that said on a pow day your fighting everyone from SLC to get up there and you usually are delayed by avalanche conditions which exacerbates the crowd issue.
Jackson still has crowds, but there is so much more terrain.The inbounds is the best I've seen outside of Revelstoke, and the slackcountry is absolutely ridiculous. And not too far away is Teton Pass which offers 4000 vert of backcountry terrain that you can lap via hitchhiking.
I'd pick Jackson any day over Alta.