As a general rule it is advantageous to file a joint return.
Brendita's statement could be a tax law violation as the rule is if you are doing MFS and one itemizes the other must also itemize; if one itemizes and the other uses the standard deduction the IRS Master Computer can catch it and you will have to pay lots of additional tax plus interest.
That said, about the only time MFS beats MFJ is if one of the two, especially the one with the smaller income, has high unreibursed medical costs or employment related legal fees. One year Judy had about $16,000 in dental work done; we filed MFS that year as if we had filed MFJ the medical floor would have been about $6,000 higher. I did maneuver the real estate taxes, mortgage interest and contributions between us for the lowest total tax. Doing it this way saved us about $1,700 on our taxes. However in "normal" years due to our differences in income MFS would always have been higher.
Mike
CPA Retired