The answer to this question is no longer a mystery. Literally the only thing that you need to do is watch how mixed martial arts has developed over the last twenty years and you have the purest example of what fighting styles work. Thousands of fights over two decades provides a pretty damn scientific answer. Primarily you need to know how to grapple. Without this knowledge there's a big chance that any striking skills will be rendered useless as soon as some thug grabs hold of you or your clothes. So if you want my advice, get a solid background in BJJ or submission wrestling. The fact that you are able to spar 100% every time that you train without getting hurt means that you will remember your training under stress. The importance of this cannot be overstated. The reason that arts like wing chun, aikido and Krav Maga do not have a history of being effective in live fighting is that they are not generally practiced in a live setting. It's simply not possible to remember how to fight if you haven't done any fighting. I've had experience in wing chun, systema and many of the arts mentioned on this thread, and the truth is they they simply don't work. Please take my word on this, take BJJ for a couple of months (multiple times weekly, this will get you MUCH faster results) and if you still do not feel confident, then try supplementing with some striking training, in boxing or kickboxing (ideally Muay Thai). The problem with these arts is that full sparring is very demanding, and it will take a lot of experience to become confident enough to throw meaningful strikes in a self defence situation. I have trained and competed in Muay Thai for three years and BJJ for just one, yet I feel that if I was attacked I would defer immediately to my grappling.
Please trust me on this, BJJ is the way to go if you want to get the most out of your time. I promise that you will very quickly find yourself becoming obsessed. The art also has a reputation for friendliness and playfulness, so you'll have **** loads of fun and learn how to defend yourself in the most effective way all while never taking a single punch to the face. Does it almost sounds too good to be true? That's what I thought. It took me years for one of my BJJ friends to convince me to start grappling, but I've never looked back.
Start your journey man, you will not regret it. See you on the mats.