If you have a mortgage, your rent payment is locked in. If you rent, you're subject to annual increases in rent (which can be steep, and higher than inflation).

There are many factors that determine if buying or renting is better for your scenario. Below is a calculator the NY Times publishes which lets you adjust variables to provide an answer based on inputs.

http://www.nytimes.com/interactive/2014/upshot/buy-rent-calc... (NY Times: Is It Better to Rent or Buy?)