I really like skiing alone, but mostly ski with others (sidecountry). My favorite part about skiing alone is being able to just ski a line top to bottom. The sheer amount of terrain we have available makes it hard to find the same line twice, and know it well enough to ride it in one go and all end up at the same place, due to complex route-finding of downed logs, cliff bands, and close-out trees. When you don't have to keep with a group, you can just ski without wondering if your friends will pick a line that'll end in the same location (rarely does that happen).
If I could always get out with the same group of rippers every weekend, then I'd change my tune. For example, two weekends ago I finally found a clean line through a couple tree'd cliff bands (been looking since last year). I was with the same group on Saturday, and since we all knew how to get down to where we needed to meet, I could send the line all in one go. It felt SOOO good, and it was especially fun to have someone to share my excitement with and pass the stoke around.