good music, technical skills but also FLOW and by this I don't mean technical flow. I've heard reputable Dj/Producers completely clash melodies/harmonies of two tracks even though the mixing and technical flow was perfect and the tracks were good as well. Villalobos is the sh!t because he constantly changes key and moves the music around into different moods by mixing musically. Lots of Dj's I've seen with good track selection and skills but the overall programming leaves something to be desired and almost always there are some awkward clashes in melody or groove
with that said, other than the created imperfect tension of good live mixing on vinyl, i dont really care how the music is delivered to me and I'd rather hear a guy take me on a journey and flub the technical stuff a little bit