As has been said, the most important thing is that he handgun fit the individual's hand. Everything else comes second (because they're so easy to deal with). Why would you want to start out with a gun that doesn't fit the individual shooter and forcing them to adapt to the tool instead of getting the tool that fits the individual anyway?
There are a limited set of grip angles, grip widths and reach to trigger in the various makes/models of handguns. If you find what make/model has a grip angle that matches the shooter's natural pointing position and fits the width of hand to width of grip you've found what "family" of handguns points most naturally for the shooter. From there you can work within that "family" to find the features to enhance the fit of the gun. These can be picking SA vs SA/DA for reach to trigger or having a trigger job done to shorten or lengthen the reach. Adding grip panels or changing grip material may be needed to tweak the gun into a perfect fit for the shooter's hand. Shaping the backstrap might be beneficial to wring that last little bit out of it.
Consider one of the new semis with interchangable back straps that change the entire grip angle if you don't find the gun with the features you want in the grip angle/width you fit.
Trouble with racking a slide? Try locking your grip on the slide and pushing the gun forward to rack the slide instead of tugging the slide back. The ergonomics are far more effective with the push than the pull. Consider having more aggressive cocking serrations a go.
Again, it's the fit of the gun to the new shooter that is the first thing that needs to be determined. All the rest becomes feature selection.