Who would win in a street fight... (which style of fighting is more effective for real world applications?)?

That's really up to the person and the type of scenario in question. You can have a really effective BJJ person or a really effective Thai boxer. The terrain and environment will also come into play. If a Thai boxer loses footing and falls down, it could be bad. If a BJJ trained individual is against someone with great evasive skills and knockout potential, it could be bad for him as well. Sometimes there's no room for punches and kicks, sometimes there is. If there is a weapon involved or multiple attackers or multiple attackers with weapons, things will definitely change. Sometimes you need to keep away. Clinching and grappling is not always the best thing to do. Grappling a person with a hidden weapon can have drastic consequences for an individual if he is not fully aware of such dangers.