I find it humorous that so many people have the idea that revolvers are "old fashioned" while semi-automatics are "new and with the times." In fact, both the Double-Action revolver as we know it today and the first successful semi-automatic handguns were developed at about the same time: 1890-1920.
Now, it is certainly true that modern revolvers are more similar to their late 19th and early 20th century ancestors than semi-autos are (though the 1911 is still quite popular), but perhaps that is because the design of the DA revolver simply had less to improve upon to begin with.
Also, much is made of the fact that police have nearly universally adopted the semi-automatic, but what is ignored is that it took a very long time for them to do so. The majority of U.S. police agencies didn't make the switch to semi-autos until the 1980's and early 1990's. This means that most cops stayed with revolvers for more than 50 years after successful semi-automatic pistols had been available. Our own military has used semi-autos since 1911 and, because many, if not most, old-time cops were also veterans it's difficult to make the argument that a semi-auto was foreign to them. It seems obvious to me that police departments saw something very appealing in the revolver to stick with them for so long after the supposedly superior semi-auto had made its debut.
So, the question then is what was so appealing about a revolver and what finally prompted the changeover. A valid argument could be made that the nature of crime changed particularly with the rise in prominence of illicit drugs. However, the drug and gang wars of the 1980's are not the only period of lawlessness in American history. Certainly the gangsters and motorized bandits of the 1920's and 1930's were at least as well armed as the Crips or Bloods of today, yet revolvers were deemed sufficient during prohibition and the Great Depression.
The answer, I think, is that not only has the nature of crime changed, but the roles and attitudes of police, particularly in regards to firearms, has changed along with them. The handgun of a cop in decades past was primarily viewed as an instrument with which to defend himself/herself should an unexpected danger arise. If the cop intended to pursue an known dangerous individual, it was expected that a more formidable weapon such as a shotgun, rifle, or submachine gun would be called upon. Today, however, there seems to be an expectation that the cop's handgun should be suitable as a primary weapon with which to go forth and confront dangerous criminals with. The perceived need for high-capacity and speedy reloads seems to grow out of the expectation that, more likely than not, the handgun will be the only weapon at the cop's disposal when pursuing known dangerous individuals.
At this point, I think it is important to make a distinction between the responsibility and needs of a cop and the responsibility and needs of a private individual. It is the job of the cop to go forth, seek out, and confront dangerous and violent people. By comparison, the private individual is responsible only for his/her own safety and that of his/her loved ones. While the cop would be expected to intervene in a dangerous or volatile situation, it would be extremely unwise for the private individual to do so if it could be avoided.
As such, I think the erroneous assumption is made that the needs of a cop and the needs of a private individual, when it comes to firearms, are one in the same. In many, if not most, cases they are not. The offensive nature of a cop's use of a firearm makes capacity and speed/ease of reloading very important, but the defensive nature of the private individual's use of a firearm makes other considerations more important. For one thing, most private individuals who carry a firearm for defensive use prefer to do so discreetly, and in many places concealed is the only legal manner in which a private individual can carry a firearm. Likewise, should the private individual find it necessary to use a firearm in self-defense, it will most likely be very close, very fast, and under less-than-ideal circumstances.
For my own needs, I find a revolver to be best suited to the manner in which I'd most likely have to use a gun defensively. For one thing, revolvers seem to suffer less adverse effects in terms of reliability when miniaturized than semi-autos do. Also, they are ideally suited for close range use because they are less likely to malfunction from a shot at contact distance or due to a less-than-perfect grip. Finally, revolvers often offer more powerful cartridges than semi-automatics of similar size and weight and since my most likely attacker would be equal to or greater in size than I am this is an important consideration to me.
Now, before anyone dredges up the old cliches about preparing for the worst-case scenario, consider this: what sense does it make to prepare for a very bad but extremely unlikely scenario at the expense of being best prepared for a more likely yet equally bad scenario? While it is undeniable that a semi-automatic is the best handgun for certain situations, a revolver is a better choice for other situations. While one person may think of being attacked by a street gang as the "worst case scenario," I think that being cornered by a 400 lb drug addict is just as bad and I'm much more likely to find myself in the latter situation.
What it really comes down to, In my opinion, is that selecting a defensive handgun is a very personal thing. Without knowing some very intimate details about a person's life, it is nearly impossible for someone else to recommend the "best" defensive handgun. I think we would all do well to remember that what is best for one person may be a terrible choice for another.