It depends on your experience as a dj.
If you like mashing buttons then get the Mixtrack Quad, down side to mixtrack Quad is it doesn’t have serato intro or dj yet.
I own the Numak N4 and you must be a quick/advance dj to use it, you also(depending on your mappings) have to hold a shift button and press the cue button at the same time to jump to a cue. I don’t think you have to do this with Mixtrack Quad. Numark N4 also comes with Serato intro(you can upgrade to serato dj) and virtual dj LE (you can upgrade to virtual dj Pro)
Here is a video of me on it.
[media=youtube]AOLMNmQhNKU[/media]