It depends on a few different factors, including how many cells your battery is. Wherever you're going to buy the motors, they likely have some information on which props they tested with so you can figure out what will work. Another place to look for recommendations is where you bought your frame from. Or search for setups that use your frame. There is no perfect answer to this question.
Also, you can use eCalc to do different calculations on your setup to figure out what is optimal: