There's really no way to answer this question as which platform is the best choice depends on you and your individual circumstances. For some situations, a high-capacity semi-auto is better and for others a revolver is advantageous. While I cannot answer the question for you, I can describe my own circumstances and the reasoning behind why I feel most comfortable with a revolver.
First and foremost, I live in a comparatively small community (less than 50k people) and violent crime is uncommon with gang activity being almost unheard of. That being said, there is a fairly significant drug problem in my community and the surrounding areas, particularly methamphetamine. Also, there are a good number of what we would describe as "big ol' boys" who are somewhat prone to less than intelligent behavior particularly when under the influence of mind-altering chemicals. I am also aware that the majority of self-defense situations take place at very short distances which are usually better measured in feet than yards.
Because of these factors, I find a revolver to be the best choice for me. First and foremost, I am more trustful of a revolver's reliability should I be forced to take a shot at contact distance or with a less-than-perfect grip. I am fully aware that techniques have been developed to minimize the chance of a semi-auto malfunctioning if used at contact distance, but because I've never had to use a firearm in self-defense and therefore do not know exactly how I would react to such a situation, I am not particularly confident that I would have the presence of mind to remember and employ said techniques "when the balloon goes up." Likewise, while some semi-autos are less sensitive to grip than others, all must have at least a somewhat steady platform from which to operate in order to be reliable while a revolver only requires a firm enough grip to hold the gun and enough strength to operate the trigger.
Secondly, the power, and in particular penetration, that is available in a revolver of reasonable size is advantageous to me. As I mentioned, there are a large number of very big people in my area. Likewise, I'm a fairly large individual myself at 6'4" tall and over 300lbs. It has been my experience in life that, more often than not, attackers prefer victims that are smaller, weaker, or offer them some other advantage. Because of this, I feel that my most likely attacker will be an extremely large person that may very well require the extra power and penetration of revolver cartridges like .357 Magnum and .44 Magnum (both of which are in my rotation of SD handguns).
Now, I am fully aware that my choice of a revolver does not prepare me as well for a multiple-attacker situation. However, it is a worthwhile tradeoff in order to be better prepared for being accosted by one or two very large individuals which is a far more likely scenario for me. That being said, I do not completely dismiss the possibility of being attacked by a larger group nor am I completely unprepared for it. I do always carry at least one reload for my handgun and often two or three. While a revolver does take more time to reload than a semi-auto and will require that practice sooner than most semi-autos, these factors are taken into account in my choice of tactics. It would be very foolish to stand stationary blazing away like Wyatt Earp in the streets of Tombstone if attacked by multiple people and I have no intention of doing that if I can avoid it. I will, if faced with a multiple attacker situation (or even a single attacker one for that matter) make every effort to seek cover or, better yet, get away both of which will increase the time and distance that I have to reload my gun if necessary. Likewise, even if my attackers do not choose to re-evaluate their life choices when bullets start flying, it is a very rare person who will not seek cover themselves or at least hesitate for a moment when a gunfight starts and these behaviors will also increase my time window to reload if necessary.
Now, I do realize that there are situations in which one cannot get away and may be forced to "stand and fight" and the most likely of these situations that I can think of is a home invasion. While I also choose a revolver as my home defense handgun, it is not the only firearm which I keep at the ready for that role. If a six-shot revolver is insufficient to defend my home, I need to be reaching for the pump-action shotgun or the semi-automatic rifle that I also keep at the ready. Finally, if I should find myself backed into a corner armed only with a handgun against multiple armed attackers who are willing to brave gunfire to reach their goal, I'm realistic enough about my skills to realize that I'm most likely sorry out of luck no matter what type of handgun I have in my hand.