What are the priorities for substituent groups on a cyclohexane?
If the numerical sequence of locants is equivalent, the numbering should be assigned to correspond with alphabetical order. Hence, in your example, correct would be 1-ethyl-2-methylcyclohexane. Quoting the IUPAC Blue Book, Rule A-2.4:


  If two or more side chains are in equivalent positions, the one to be assigned the lower number is that cited first in the name.