In most locations, you might have a point. The original poster lives in California, where (AFAIK) anything larger than a 10-round magazine is illegal. There is something nice about a 15-round mag, but not if owning one will get you arrested.

Given this restriction, a Glock will only hold four rounds more than a revolver. I say go for the revolver.

Now, if a person wants to shoot as a hobby, a nice little 9mm semi-auto will be far easier on the wallet for an hour or two at the range than any other centerfire caliber known to man. Semi-autos are also simply more fun than revolvers, IMHO. But that is another discussion entirely.