The phrase "a land which is choice above all the lands of the earth" (Ether 1:42) is covenant related. For example, we also find evidence of this same covenant phraseology in the following verses:
And inasmuch as ye shall keep my commandments, ye shall prosper, and shall be led to a land of promise; yea, even a land which I have prepared for you; yea, a land which is choice above all other lands. (1 Nephi 2:20, italics added)
Nevertheless, thou beholdest that the Gentiles who have gone forth out of captivity, and have been lifted up by the power of God above all other nations, upon the face of the land which is choice above all other lands, which is the land that the Lord God hath covenanted with thy father that his seed should have for the land of their inheritance; wherefore, thou seest that the Lord God will not suffer that the Gentiles will utterly destroy the mixture of thy seed, which are among thy brethren. (1 Nephi 13:30, italics added)
But, said he, notwithstanding our afflictions, we have obtained a land of promise, a land which is choice above all other lands; a land which the Lord God hath covenanted with me should be a land for the inheritance of my seed. Yea, the Lord hath covenanted this land unto me, and to my children forever, and also all those who should be led out of other countries by the hand of the Lord. (2 Nephi 1:5, italics added)
And it came to pass that Jared spake again unto his brother, saying: Go and inquire of the Lord whether he will drive us out of the land, and if he will drive us out of the land, cry unto him whither we shall go. And who knoweth but the Lord will carry us forth into a land which is choice above all the earth? And if it so be, let us be faithful unto the Lord, that we may receive it for our inheritance. (Ether 1:38)
And the Lord would not suffer that they should stop beyond the sea in the wilderness, but he would that they should come forth even unto the land of promise, which was choice above all other lands, which the Lord God had preserved for a righteous people. (Ether 2:7, italics added)
For behold, this is a land which is choice above all other lands; wherefore he that doth possess it shall serve God or shall be swept off; for it is the everlasting decree of God. And it is not until the fulness of iniquity among the children of the land, that they are swept off. (Ether 2:10, italics added)
[Alan C. Miner, Personal Notes]