I've never done fireworks at either location but find Cali Grill to be the superior dining experience.
I've found Narcoossee's to be somewhat less polished (i.e., in atmosphere, service, presentation, and execution) than most of the other resort signatures at WDW, including Cali Grill. I also find their menu somewhat lacking because, to me, their signature items (particularly their lobster entrees) seem grossly overpriced (even by WDW standards) and most of their other, less expensive entrees usually seem somewhat underwheming. I do, however, love the almond crusted cheesecake dessert.
To me, Cali Grill has a more unpscale atmosphere, better service (usually), better presentation, and a much broader and deeper menu that is better executed than Narcoossee's. For example, when I go to Cali Grill, I'm usually struggling to decide between at least 2 or 3 entrees that look really appealing whereas at Narcoossee's, I'm struggling to find 1 thing (other than the overpriced lobster) that looks really appealing. On the other hand, I've found Cali Grill to consistently be the busiest of all of the resort signatures, which can sometimes negatively affect the service (although, for us, service has usually been excellent).