It's best to try before you buy.
1) Attend gun safety training if you have not yet done so. NRA Basic Pistol or NRA Home Firearms Safety are good courses that focus upon safety.
2) Borrow or rent various handguns in various calibers.
3) Attend a two day "Level 1" self-defense handgun course since your stated goal is self-defense. You don't know what you need in a gun (and gear) until you have learned to run one. The instructor will have various guns and gear available.
If you don't do #3, then at least buy several private lessons at the local gun range.
The SIG P226 Navy is going to be hard to come by. It's really more of a collector's piece.
Para Ordnance...avoid them. Every friend of mine who has had a gun from them experienced reliability issues.
Revolvers are a whole different game. They require much more diligence and training to learn to run properly. Some people on the 'net and OCDO will claim revolvers are "easier" to use. Running a revolver is far more difficult. You'll need to so some research. Also keep in mind there are few trainers who are proficient in training people in the use of revolvers.