I use and recommend Ableton live, it's awesome but a lot of people seem to find it a bit daunting at first.
Traktor is good, but I think it's more better suited to traditional DJs trying to adapt to digital music production or people that just wanna play around.
If you just wanna spin tunes, I would def go with Traktor, it's heaps of fun. I would use it more if it supported plugins (it doesn't have AU or VST support, just built in plugins, reverb etc).