Use getters, if you have them!
Maybe, one day you change the code so that a getter will not only return the fields value but do something more or create the result in a different way. Then you'll be more then happy that you used getters consistently.
But as usual, there are excemptions from my advice - what do you expect from the toString() method if you allow overriding of the getter methods, do you want it use the classes fields or the result of the - maybe override - getter method.
So, as usual, it depends, but I'd use getters unless I have a good reason to access the fields directly.