君こそ

you, of all people

→ 君
phrase Rare #23,813
you, of all people こそ emphasizes 君, often highlighting that the person being addressed is the one in question. 君 can sound informal or overly familiar depending on the relationship.
JA: 君こそ私が会いたかった人だ。
EN: You’re the one I wanted to meet.

君こそこの前のとき退屈そうにしてただろ?

You were the one who looked bored last time, weren't you?

— グッドフェローズ (1990)

君こそ彼と話した方がいい

You’re the one who should talk to him.

— Hoje Eu Quero Voltar Sozinho (2014)

君こそその仕事に最も適任だよ。

You’re the best person for the job.

君こそ私が探していた人だ。

You’re exactly the person I was looking for.

君こそ元気で

You take care too.

— ザ・マン・フロム・アース (2007)

君こそなぜ?

Why you?

— パディントン2 (2017)

君こそ本当の働き者だ。

You’re the real hard worker.

君こそペテン師だ

You're the con artist.

— エリート・スクワッド ブラジル特殊部隊BOPE (2010)

君こそ雨の中大変だったね

You must have had a hard time in the rain.

— 魔女の宅急便 (1989)