BC - do you have a favourite between Nightfighter Ace and Interceptor Ace? I'm more pulled towards Nightfighter Ace myself.
Good question.
I've not played Interceptor Ace though I've poured over the content and rules (I helped them proof the rules and they put my name in the credits - LOL), so I'm fairly familiar with Interceptor Ace.
IA is pretty much the same as NA, though there is a major difference - IA has more rules for dog-fighting. Since IA deals with daylight bombing, you will be dealing with daylight interceptors escorting bombers (not always, but your odds with encountering them will grow greatly as the war progresses, as the Allies add fighters with greater ranges). NA deals with dog-fighting Mosquitoes, but I've yet to get so far in the game that they make an appearance (they CAN appear early in the game, but I've never rolled to encounter one).
It also depends on your own tastes. If you like the idea of flying night fighters against Bomber Command's raids, NA is for you. If you enjoy the thought of flying against American bombers during daylight raids, that's for you. Really, two sides of the same coin, but since IA came after NA, IA incorporates some more polished rules...though that's nothing I'm meaning to slight when it comes to NA.
So, NA is more about fighting bombers, while IA is more about dog-fighting AND bomber attacks.
Another one I have that I've not gotten to is Skies Above the Reich, a solitaire game where you command a squadron of German interceptors (rather than one, as in IA and NA). SATR might be an option though it's expensive, component-heavy, and not focusing on just one fighter, which has a good amount of appeal to me.
I know I've not given you a definitive answer, and that's on purpose - it really depends on your preferences, and I tried to detail some of them here. I had bought NA because I'd had zero idea of night fighting efforts in World War 2, and it opened up avenues of further exploration (buying books and learning a great deal more on the subject). Whereas, there's a right plethora of books on daylight bombing, there aren't as many on night fighting.
Hope that helps, but if you have any other questions don't hesitate to ask.