For the 'occasional' user or shooter...
A fixed sight, medium frame, double action revolver in .357 Magnum.
A single action could do, but for 'casual' shooters, the double action is probably easier to use.
My personal preference is for K frame S&W revolvers, but I would jump on a Ruger Sxxx-Six revolver (any of them) in a second. (The Security, Service and Speed-Six revolvers were the predecessor to the GP100 series, for those who came in late.)