MFS = Married Filing Separately
MFJ = Married Filing Jointly
Unless you live in Ohio and both have income, you will almost certainly pay less tax or get a bigger refund by filing jointly rather than separately. But to file jointly you both have to agree and cooperate. If that's not possible, then your only choice is married filing separately.
If you have a child living with you, post more details, including the child's age and exactly when and for how long he or she lived with you. Also clarify for which part of the year you and your wife lived separately. As Carl said, there might be another option if you have a child living with you.
