Most efficient way to compare multiple arrays based on a fixed element and copy the largest one?

I’ve four arrays of length 18 (k1,k2,k3&k4). I want to compare the last element of each array & copy the contents of the array with the largest final element.

Currently, this is how I’m doing it:

if (this.k4[17]>=this.k1[17] && this.k4[17]>=this.k2[17] && this.k4[17]>=this.k3[17])
            m = this.k4.filter(() => true);
        else if(this.k1[17]>=this.k4[17] && this.k1[17]>=this.k2[17] && this.k1[17]>=this.k3[17])
            m = this.k1.filter(() => true);
        else if(this.k2[17]>=this.k4[17] && this.k2[17]>=this.k1[17] && this.k2[17]>=this.k3[17])
            m = this.k2.filter(() => true);
        else
            m = this.k3.filter(() => true);

But this isn’t scalable incase I added more arrays in the future.

Here is another method:

var maxlast = [this.k1[17],this.k2[17],this.k3[17],this.k4[17]];
var max = maxlast.reduce(function(a,b){return Math.max(a, b)}, -Infinity);
var pos = maxlast.indexOf(max)+1;
m = eval("this.k"+pos+".filter(() => true);");

I’ve heard eval() is a major security risk, is there an alternative approach?