I used Starry Night Deluxe (no longer made) and now use Starry Night Pro and XEphem, but there are a large number of different planetarium-like programs. I say planetarium-like because some of them are oriented more toward specific observing tasks.
- Starry Night — A family of programs which currently comes in three flavors: Backyard, Beginner, and Pro. They used to make a Deluxe edition somewhere in between the Beginner and the Pro. Starry Night is well regarded, particularly for it's imagery but it is hard for me to compare it with other software, e.g., The Sky because the latter would more properly be compared against Starry Night Pro.
- XEphem — a Unix/Motif program which does a great job at a number of observation-related tasks including producing sky charts. It can't be compared to Starry Night, or most of the other Windoze products simply because it never tries to product photo-realistic imagery. I love it because I can plug in the entire USNO A2.0 catalogue (6.5 Gbytes!) without having to reformat it (something I would have to do for Starry Night).