If I had to choose which to train in, I would choose Kung fu in say choy li fat or crane or one other of the many good combat effective systems. I would not choose Tae Kwan do because so many of the schools for that styel are not teaching it as a combat efficient and effective system aimed at self defense and survival. Most seem to be teaching it for Olimpic competition. and in my opinion good judo schools teach better for the street then most of the sport tkd types seem to. ( at dan level the good judo schools teach basically all the stuff that was taken out so you learn the old school Japanese jujitsu techniques and strikes and things that were removed for safety.)
This is unfortunately true so far as many (or even maybe most) TKD dojangs go, but I think it's going to be changing. TKD has been, I think, under increasing pressure to show its bona fides as an effective defensive combat system (something no one would have questioned about 'old-school' TKD). And there are a lot of people doing TKD who don't want to be competitive athletes in that particular sport (even if it were realistic on their part to pursue that path, which for many is not the case); what they want are practical SD skills, and the training to make those skills operational under street conditions (which is a very specific and 'hard' kind of training that is still pretty scarce, I'd bet, not just in dojangs but in MA schools across the whole range of different styles).
Wait a few years and I'm guessing you're going to see a lot more SD in the curricula of most TKD dojangs. The question is, how well do TKD instructors actually control the necessary combat skills themselves? Before the dojangs start teaching revitalized SD-oriented TKD, instructors themselves are going to have to come up to speed on these techs... because so many of them learned their TKD in sport-oriented schools. My feeling is, that cycle has to be broken, and soon.
But the same problem could well affect any given KF school too—there's no guarantee that your instructor there is competent in CQ combat applications either. KF also has a 'performance' aspect, after all, and it's probably the case that some schools emphasize that to the detriment of gritty applications...