Assuming that one of the seven names is the real Red John

Everybody thinks in height, short hair and all of these superficial things that are common to a high percentage of the men in America, but the smell...

The smell is very important. (“She smelt of sweat and strawberries & cream”)

We know

"he smelt of pine and nails and earth"

...and the strong hands

I think he lives in the countryside

For these reasons and because is the most unthinkable

My vote is for Sheriff Thomas McAllister