If you're going to guide a mount using a PC, then start with The Sky -- you'll end up there, anyway.
I know folks who use Starry Night for that, but I've watched them and find that The Sky is much better.
I do have copies of Starry Night Backyard, Stellarium, Celestia, and Cartes du Ciel.
I find that Celestia is very nice for making visualizations such as viewing the Earth from the Moon, and the like. But I do not like it for anything else.
I find that Stellarium is a very good program for locating things in a simulated planetarium view, but it does not seem to have many more features that I'd use.
I find that Cartes du Ciel is pretty much unbeatable for making custom star charts, but it's a bear to learn to use. Even so, I'd recommend it. There are plug-ins and companion programs for it, too -- if you buy the CD version. I recommend you download the free version just to try it out, then if you like it buy the full-up CD version (support your local programmer!).
Having said that, I must add that Starry Nights is very good for making (recording and saving) "tours" and that includes more multimedia options than any of the others if you get the "pro" versions. It is a very nice program. I have no looked at the list of supported mounts ...
Overall I use The Sky. You can often buy introductory versions for about $10 on eBay, then pay under $100 to upgrade it to higher versions (more capabilities) at Software Bisque. Still, if your goal is to drive a mount from your PC, go ahead and bite the bullet on the full-up Pro version. I think you're likely to end up there eventually ...
Just my $0.02 worth ... !!
The universe is not only stranger than we imagine, it's stranger than we CAN imagine. --- JBS Haldane
Come visit me at Comanche Springs Astronomy Campus (we're on Google Maps) in Texas.