I use this one - AVS DVD Player.

Along with DVDs it plays H.264, 3gp, Quicktime, WMV-HD and others. Comes as freeware, no ads or spyware, and includes some interesting features like changing aspect ratio or bookmarking your favourite spots in a DVD. Has a nice audio processing feature which makes stereo files sound like 5.1 or 7.1 surround!

Quick grab AVS DVD Player at http://www.avsmedia.com/DVDPlayer/