The value of q for the reaction is opposite. In this case, the equation describes what happens to the chemical reaction . If you do the calculation this way, the sign on q is correct for the q of the reaction. By the first method, you had to change the sign of q to get the value for the chemical reaction. By the second method, you didn't.
Students often wonder which calculation method is better.
The answer is that either is OK as long as you are clear about what heat you are calculating so that you give q for the reaction the correct sign in the end. Some students like the first method because it matches the general convention of final minus initial. But you have to remember that q for the reaction is opposite of the answer you get by this method. Other students like the second method because it gives the q for the reaction directly. But you have to remember that in all other thermochemical calculations you will be doing final - initial.