Best Panorama Stitching Software?

It's been years since I created a panorama with anything besides a smartphone and I don't even remember what program I was using back in the day. Since the stitching feature is not built into my Pentax DSLR, I'm stuck looking for the best computer program to use.

A Google search offered up several good looking options but I'd rather have some input from folks on here first.

I have a PC, but since this info might be useful for others, let's hear about all the options.