Through my experience I’ve used both Virtual DJ and Traktor Pro.
Both have their advantages, and both you can try before you buy.
Virtual DJ is much simpler. This is how I started DJing at a pretty young age.
Traktor is more complicated but a much better application. I personally think it’s more professional and, depending on your Controller/What decks you’re using, I think Traktor integrates better.
Ps, if you have the money, get the Mac. Again, having used both, my macbook is so much better. But then again, my PC was pretty cheap.. The mac is an investment though. I look forward to having mine for another 5 years.