[nikola_blin]

var array1 = [0.7,1,2,3];
var array2 = [1,1,2,3];
var array3 = [2.8,1,2,3];
var array4 = [0.8,1,2,3];
var array5 = [5,1,2,3];

var array_all = [array1,array2,array3,array4,array5];
var array = array_all[0];
for (var i=0; i < array_all.length; i++) {
    var array_in = array_all[i];
    if(array_in[0] > array[0]) array = array_in
}


alert (array);

Чёрт.... спасибо огромное