most useful of all the others

Although this app takes a bit to get used to, it becomes very easy to sort your tracks and use. Its very reliable; Ive never had a problem.
I find the auto bpm function to get you within points of the target; very handy. I usually tap my own towards the end of a track, to ensure a good match (doing this resets the bars to the beat, which is rarely consistent through a song, in order to ensure a matched transition.
More than the other dj apps, this one is great for seeing where things are time-wise which helps you estimate song intro lengths and make clean cuts and fades.

Taiga7 about Touch DJ™ Evolution - Visual Mixing, Key Lock, AutoSync, v1.2