I am a mobile DJ & former club DJ.
Personally, I use
MegaSeg on my Mac. It is not the greatest software out there but does do a fair job after you take the time to learn and set it up. I still like the offerings on the PC-side much better as they have better automation features.
IIRC, Final Scratch is a hardware/software interface with Traktor that allows you to use a couple turntables to control the mix. If you desire a hands on mixing solution, this is truly the only way to go. Since I never did much cutting or scratching myself, I couldn't see the point of still needing to lug in tables to every event. Although, I might have considered it for a club install as you have different needs in those situations.
I haven't played with stand-alone Traktor much as when I was doing feature set evaluations for my business, it lacked in a few key areas for our needs. Once I get some time I do plan to play with the demo, but I'm currently regenerating the library since my Echo Audio card is revealing the limitations of CBR128 AAC.
There were a few other Denon-styled software packages out there such as
DJ-1800 or
Baytex Party! I haven't tried these at all however.