Most software today is available for both Mac and Windows, and loyalists to either platform will want to stay with what they know. Mac enthusiasts boast the stability and power that one-manufacturer uniformity brings, while PC enthusiasts have the largest market share, which breeds more end-users, as well as more hardware configurations at differing price points.
For mixing music there are many excellent programs — Traktor Pro, Virtual DJ, PCDJ, Serato Scratch, Ableton Live and Mixmeister Fusion all immediately come to mind. The options for mixing music videos are more limited, with Virtual DJ, Serato Scratch and Fidelity Megaseg being primary options. Choosing your personal favorite is like choosing a car; each one has strong features and functions that are great for different people. Go online to the different manufacturer Websites and download the free demos to try out. Think about how you will use and configure them. Do they restrict your hardware setup? Do you prefer using timecode vinyl/CDs over a MIDI controller?
While trying the demos, look through the message boards/user groups. The more people talking means the more people using and therefore purchasing and supporting the software. More support means more updates and the likelihood of long-term support. Message boards will also give you a better idea of how strong and stable the software is. There is a lot of hype and marketing out there, but power users cut through that quickly.
For software, check with the people you know and your DJ idols. Superstar DJs may take a check to endorse a product, but if it doesn’t work right, they won’t rock it onstage. Those around you can also be quick and reliable sounding boards as you face setup issues and questions. Also, check with sites like DJTechTools.com for reviews from people who actually use and live with the software and hardware.