Let me start by what my definition of Beginners would encompass: A child (under supervision of an adult), an adult, who is either male or female, and who has had no previous experience with shooting a handgun. Given that definition I would recommend a Ruger IV 22/45 .22 LR pistol with a 5.5 inch barrel with a 10+1 capacity. My reasons are as follows: 1.) Given proper instruction it allows the beginner to concentrate on the basics of proper learning without having to anticipate recoil and loud noise which leads to development of flinching, pushing, and closed eyes before discharge. 2.) It has the heft, weight, and feel of many other handguns offered in some larger calibers to which one could transition to in the future after the proper basic handgun shooting techniques are learned. 3.) The trigger pull is not too heavy or too light. 4.) It has an adjustable rear sight. 5.) It is built solidly and the action has been proven over a long period of time to function reliably. 6.) Ammo is readily available, relatively cheap, and comes in a wide variety of offerings. 7.) It is within a reasonable price range of $375 - $425.
There are certainly other choices available; however whatever that choice may be the main concern has to be is that handgun must be “beginner user friendly”, and having that beginner looking forward to the next shoot, rather than turning their initial experiences into something unpleasant, developing bad habits, or scaring them away from shooting altogether...I believe that the Ruger IV 22/45 would be a very good candidate to accomplish that purpose.