This street vs ring argument crops up a lot, and it comes down to a few factors.
No amount of "dirty techniques" are going to win a fight for you if you don't know what it feels like to be hit/grabbed/tossed around and do the hitting/grabbing/tossing yourself. Live sparring and training is what makes sport fighting what it is, and it's what makes it effective.
An effective delivery system is an effective delivery system, whatever you want to call it. A jab is a jab, no matter what art it shows up in.
Sucker punches suck. No one can train you to defend yourself from a threat that you don't know is there. The thing to do here is to practice being aware of your surroundings, and use common sense, like keeping your head up when you're pushing your groceries to the car instead of looking at the receipt, staying in well-lit areas, etc.
I've found largely that people who are worried about being attacked on the street and are afraid of it often attract their own problems. A number of muggers have said on record that they choose victims based on their posture, walking gait, etc. Confidence indicates that you're not an easy target. Stand tall and relax. Sometimes a smile, a nod, and a friendly "Hello" is enough to disarm a situation before it even starts.
Eye gouges/groin strikes/etc may or may not stop fights. There is no universal OFF button. It's like people have this illusion that somehow if you put a ring fighter in a street fight, he wouldn't also be able to do all of those techniques himself. In fact, he'd probably have a better chance of making them work, as he's used to dynamic movement and could probably put more power behind them too.
As far as groundfighting goes, yes, some fights end up on the ground. Some don't. It's still good to know what to do when/if you get there. The broken glass/gravel/dirty syringes/whatever argument is kind of silly, and assumes that the other person you're rolling on the ground with wouldn't have to deal with the same thing.
The "multiple attackers" angle holds some weight, in the sense that if you're surrounded by a whole gaggle of people, yeah, you're probably going to get your ass kicked, and you're better off running. No matter what you train in, there is no solution to dog pack mentality. The best idea here is to walk with friends if you're in a rough neighborhood, or better yet, don't go to places where you know there's a high risk of getting jumped. If you're stuck in a neighborhood like that, learn confrontation management, and/or buy a gun.
On the other hand, you're not always going to be by yourself when a fight breaks out, especially the way most fights go, being the posturing/pissing contests that they tend to be, you'll be in a group of people. Sportfighters have friends too, and odds are, they're better able to get their hands on somebody and show them a rough time than the friends of the tool who decided it was a good idea to throw his beer on you, or whatever.
So, to the original question: there are several arts that offer effective delivery systems. Muay Thai, Boxing, and Judo, for example. There are many others I didn't name. Basically what you're looking for is training with resisting partners, and a school that will pressure test your techniques.
Best to you.