at best

at (one’s) best

In one’s prime, most positive, or most adept condition or state.

I am not a morning person, and I won’t be at my best until at least noon.

He was at his best about five years ago, but his performance has really started to decline lately.

She was at her best in the new film.

1. In the best possible scenario.

At best, Doug will be only an hour late.

They’re only selling junk at the yard sale, so I think they’ll make $10 at best.

2. Ideally suited for success. In this usage, a pronoun is used between “at” and “best.”

I’m not at my best when I’m tired.

Of or at the highest standard of quality possible.

You’ll love their new album; it’s simply jazz at its best.