The best Martial Arts?
If you are looking for the ultimate defense in a close up street fight, I would have to advise good striking art, I have personally trained in Ninjitsu, Jeet Kun Do, and Mantis Kung Fu, for 27, 23, and 16 years respectfully.
I have engaged in combat in many different combat situations (street fights 1 on 1 and even 6 on 1), in Chicago, New York, Los Angelas, and many other Major Cities, and I have not lost one fight in my entire life, least of all with a grappler. With good training in any of the Arts I have studied, or any of the likes, you should be able to take on most combat situations, with great confidence, and success.
For the most part, Grapplers are reliant on circumstance, and trying to keep you off balance, if you can see the attacker coming, especially a grappler, and you can react quick enough, you should be able to drop your attacker with one well placed attack, atleast lomg enough to get away.