Dude, be more particular with the details of the car rather that its maker ;)

Should both have the same mileage & same price, but you have to look under the hood, in the chasis.

You should also take in consideration the kind of driver the current owners are. If they use their respective cars off roading, etc. Check the Service book as well if its upto date.

Mazda or Nissan, both have a reputable name in their cars. So just look at how the owners used their cars ;)