Sunday best

any given Sunday

On a particular day, an unpredictable outcome can occur.

as best one can

In the best possible way, given one's circumstances and abilities.

best bet

The best proposal or plan.

best laid plans

A proverbial expression used to signify the futility of making detailed plans when the ability to fully or even partially execute them is uncertain.

best of both worlds

A combination of two seemingly contradictory benefits.

best of the bunch

The best or most preferred person or item within a group.

best pleased

displeased, upset, disgruntled

best regards

Used as a polite closing of a letter