Respuesta:
I think "most/more common" are the most commonly used forms, as well in the UK as in the USA. Anyway, commoner and commonest also exist, but they are more common in the UK than in the USA. In fact, "commonest" is rather common in UK, and "commoner" is uncommon in both countries (on the other hand, "commoner" is also used as a noun: a person who is not a member of a noble family)
Explicación:
Espero te sirva
