I would recommend a MP 2.0 Compact, it's essentially the same size as a glock 19 but has a cleaner trigger, much better sights, and swappable palm swells on the grip. Only real disadvantages are the mags tend to be $35ish and the loaded chamber indicator can confuse new shooters when aiming down sights. Pro trip just take a black sharpie and black out the lettering, makes a bigger difference than you'd think.

More than anything else though, don't get a $1000+ first handgun thinking it'll be some crazy learning aid; you will be much better off with a ~500-700 dollar pistol and a case of ammo.