Oh, jeez. I don't know if I have a favorite. :x
I guess I tend to judge violininsts on a case by case basis, but some of my personal favorites are David Oistrakh, Michael Rabin, Leonid Kogan, Izthak Perlman, and of course Nathan Milstein, Henryk Szeryng and Yehudi Menuhin.
In my view they're all great in their own ways, and on pieces by certain composers some seem to excel where others would not. Milstein is godly when he's playing Bach and Paganini, but he really wouldn't be my first choice for a piece by Tchiakovsky or Brahms. That seems like it would be better suited to someone with more romantic flair, like Heifetz.
So I guess it's all really subjective to me.
Menuhin plays Paganini Concerto No 1. Those double stopped moveable harmonics! I'm going to need a defibrillator. :O