@maporsche,
For quality and punch, I suppose I would go with a S&W Model 19. That's a .357. Personally, I favor the S&W J frames (Chief Special, mostly), but I'm giving up the punch in favor of something that fits better in my hand. Also, and just personally, I don't like the .357. I don't like the sharp recoil and the high pitched report.
I think the .45 auto is ideal for defense, but since you said revolver, that's how I'll answer.