Eminence is "Fair"

Bit of a thought experiment, but if you could change the text of any commander to include "eminence" on any ONE of it's applicable abilities, which would be the strongest and which would be the most interesting for you to build around? Which ability of said commander are you giving eminence?

In the interest of making it more interesting let's only consider commanders with a CMC of 4 or greater and the ability cannot target or directly impact opponents (think [[Elesh Norn, Grand Cenobite]] giving opponents creatures -2/-2).