That depends upon many things. Generally filing jointly results in less tax owed, especially if spousal incomes are different. However, filing jointly means you will be taxed on your spouse's worldwide income (assuming he or she is not a US Citizen) even if the US would not ordinarily tax such income (because a non-citizen spouse not in the living US is not usually subject to US taxes).
Unfortunately the only way to know for sure is to do it all three ways (joint, each of you filing separately).
If you were married on 12/31/2017 you must file as married. (But can file jointly or separately). If you were not married on 12/31/2017 you must file as single.
You might find this TT article helpful.
Also if you were married last year (2017) and your spouse was not a US resident or citizen in 2017 and you decide to file jointly, you must follow the instructions below to make an election to treat your non-resident spouse as if he or she were a resident. (See "how to make the choice")
<a rel="nofollow" target="_blank" href="https://www.irs.gov/individuals/international-taxpayers/nonresident-alien-spouse">https://www.irs.gov/individuals/international-taxpayers/nonresident-alien-spouse</a>