Bath fly-half Ford is the England incumbent after a starring role in this year's Six Nations while Farrell was injured.
But the Saracens man - who appeared in the decisive third Test victory over Australia in 2013 - returned to action later in the season and led his club side to the domestic title at the expense of Bath and Ford.
And the recently-retired Cueto admits there is little to choose between the two: "Fly-half is a real headache because they are very different in the way they play.
"Owen is very defence-orientated; he is aggressive, strong in tackles and if there is a penalty in the dying seconds he is your man to take it.
"George is more of an attacking fly-half who looks to get the backline into the game a little bit more.
"In terms of tournament rugby, Owen is your man from a consistency point of view and knocking the three points over.
"If I am going purely on a results point of view I am going with Owen but at the moment, purely of the back of Six Nations, if is probably 51-49 to George at the minute."
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