I think two subs to 14 is definitely the way to go. Sink a carrier and not have to fight the fighter!
I also think Africa is not worth the effort for Germany, so its worth dumping a unit in Gibraltar is worth taking away a UK fighter. Even though it’ll cost you the transport, if you’re not going to go for Africa, its an acceptable loss. (I even sometimes tank the armor from Africa and put it in Gibraltar. Sure I’m stranding a tank instead of any infantry, but its a tank that won’t to any more than have a 50-50 chance of knocking out an allied infantry when it is attacked, so I might as well waste the tank instead of an infantry from Europe.)
If your strategy involves pushing Africa or the Middle East with Germany, I still think its worth going after that carrier, but better to save your transport and let that UK fighter live to fight another day.