New Revised Standard Version
Saul and the people spared Agag, and the best of the sheep and of the cattle and of the fatlings, and the lambs, and all that was valuable, and would not utterly destroy them; all that was despised and worthless they utterly destroyed.

Contemporary English Version
Saul and his army let Agag live, and they also spared the best sheep and cattle. They didn't want to destroy anything of value, so they only killed the animals that were worthless or weak.

New American Bible
He and his troops spared Agag and the best of the fat sheep and oxen, and the lambs. They refused to put under the ban anything that was worthwhile, destroying only what was worthless and of no account.

Douay-Rheims Bible
And Saul and the people spared Agag, and the best of the flocks of sheep, and of the herds, and the garments and the rams, and all that was beautiful, and would not destroy them: but every thing that was vile, and good for nothing, that they destroyed.

And Saul and the people spared Agag, and the best of the flocks of sheep, and of the herds, and the garments and the rams, and all that was beautiful, and would not destroy them: but every thing that was vile, and good for nothing, that they destroyed.

the best

1 Samuel 15:3,15,19 Now therefore go, and smite Amalec, and utterly destroy all that he hath: spare him not, nor covet anything that is his: but slay both man and woman, child and suckling, ox and sheep, camel and ass. . . .

Joshua 7:21 For I saw among the spoils a scarlet garment, exceeding good, and two hundred sicles of silver, and a golden rule of fifty sicles: and I coveted them, and I took them away, and hid them in the ground in the midst of my tent, and the silver I covered with the earth that I dug up.

the fatlings.

2 Samuel 6:13 And when they that carried the ark of the Lord had gone six paces, he sacrificed and ox and a ram: