Because thy loving-kindness is better than life - Thy favor; thy mercy. This is of more value than life; more to be desired than life. Life is the most valued and valuable thing pertaining to this world which we can possess. See the notes at Job 2:4. But, above this, David valued the favor and friendship of God. If one or the other was to be sacrificed, he preferred that it should be his life; he would be willing to exchange that for the favor of God. Life was not desirable, life furnished no comforts - no joys - without the divine favor.
“My life itself, without Thy love,
No taste of pleasure could afford;
‘Twould but a tiresome burden prove,
If I were banished from the Lord.”
My lips shall praise thee - That is either
(a) because of this loving-kindness; because I have this trust in thy character; or
(b) because thou wilt restore me to the place of public worship, and I shall be permitted again to praise thee.
Probably the latter is the true idea.