I usually prefer "The Panorma Factory" (
http://www.panoramafactory.com/), one of the most powerfull panorama software I've ever found.
Such a power makes obviously the software quaite complex, but it has a beautiful wizard, that in very few "next>next>next...", gives you always stunning results!
During the stitching process, "The Panorma Factory" is also able to detect (from EXIF data) the camera model and the focal lenght used to take the picture, so it's able to "automagically" correct some known aberration in perspective lines.
The latest version is Shareware (~$60), but there's also a freeware version, that lacks the wizard, but works fine anyway.
If you wish, you may check out some pictures of mine here:
http://www.b2t.biz/B2Tblog/gallery/22.aspx
Last but not least, "The Panorma Factory" is also able to produce 360° QuickTimeVR movies. But in this field, I definitely prefer iPIX, which requires a fish-eye and a special tripod, but lets you experience the "true spherical immersion" in your pictures (check it out here
http://www.concazzurra.it/iPIX/ConcaAzzurra_360.htm and here
http://www.ispionline.it/it/ipix/palazzo_ipix_ballo.htm).