Trauma

With that logic I'd say Toru Okada.
Good emotion, no squawk.

Normally I'd say Portrait, Pg. 99, or C.O.C., something like that.
But since this is such a difficult question just because there are so many good screamers out there, I'll just list the ones I think use the most technical-precision and out-of-the-box ideas in their vocals:

Crestfallen, Jerome's Dream, The Kodan Armada, Bravo Fucking Bravo, and fucking Takaru.

I Would Set Myself On Fire For You do pretty average vocals for a screamo band that likes to have normally sung melodic lines, but they get props for passing the vocals around in a 3-person circle mechanism, that's pretty tight.

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A mi no me importa nada
Para mi la vida es un sueño