Perfection
Sherlock knows that kissing requires coordination. A perfect kiss is between two people who know each other well and coordinate each other.
An ideal kiss would not involve biting, laughing in each other's mouth, or stopping to wipe your mouth dry. It would entail neither noses bumping nor accidentally cutting the other's lip with your teeth. It wouldn't be fast paced, desperate, hungry, possessive, and a fight for dominance or a metaphor for intercourse.
Lestrade doesn't kiss Sherlock in a perfect way. His kisses are real: passionate, sweet, sometimes too eager, sometimes teasing for hours on end, when Sherlock decides to play along.
But to Sherlock, Lestrade's kisses are the closest to perfection.