The most popular DVD players on PC in the world is WinDVD and PowerDVD.
Which should I choose?
Choose PowerDVD 5:
If you want to go with Cheap, Cool skin style(Interface), good feature, and Easy to use, then, PowerDVD is yours.
Choose WinDVD 5 Gold or Platinum:
If you want to go with Expensive, Decent interface, Advanced feature, and Better sound, then, WinDVD 5 is yours.
Is there any other DVD software that's good, but underrated?
Yes, there are many out there.
If you want to go with Cheap, Somewhat decent Interface, Advanced feature, Easy to use, Support all disc and formats, Surround Sound Effect, Audio & Video formats conversion, Make vague video has high definition, Better value overall for your $ , then choose Hero Super Player 3000.
You can try it by download it from CNET.
For me, I use both PowerDVD and Super Player 3000, PowerDVD is fine for me, because I rarely watch DVD on my computer. Super Player 3000 basically has all the feature that you need in a DVD and video player, and It has some other great feature that both PowerDVD and WinDVD lack.
This is not professional opinion, it's just some basic that we all should know, it's my own personal opinion, I think it will be great to here all your opinions about DVD players.