Agree with Mr. T. Go to a range, rent several, and figure out what you are most comfortable with.
this is a good idea
I'm a former military police and a avid shooter for 30 years. I have seen people choose SD guns over style and even color. This is not the way to approach it.
The semi auto handguns are better for SD in my opinion because of the larger capacity, but you have to be able to handle them properly or they can fail
For instance, a semi auto works off of blow back force. (Simple science, Newton's 3rd Law) So if you fire one and don't hold it firmly enough in your hands, the motion needed to eject the old case and load the next one may not be sufficient and you could end up with a malfunction. If you have a bad guy coming at you, can you think and move fast enough to clear a jam and get back into firing position?
It is for this reason that I started my wife out on a snub nose revolver.
All you do is aim and pull the trigger. Period
A Ruger SP 101 is one excellent choice. It is a 357 Mag with but you can practice inexpensively with 38 Special ammo
The air weights are good, but are very hard to manage recoil with SD ammo and can give the new shooter a bad experience.
Once you have had experience and can clear a jammed gun, then consider carrying a semi auto.
Whatever gun you choose, train like your life depends on it
One question I have to the OP
How will you want to carry this gun. Vehicle / Home only? On your person?
Concealed or open?