My list in no particular order:
1. .45 auto, 1911 of course.
2. .357 mag DA revolver. S&W or Ruger.
3. .22 auto pistol. take your pick
4. 9mm, Any good military type. (For cheap range time.)
5. One totally impractical, large caliber, massive, heavy, long barreled
handgun. (just...