9 mm gun, what to get?

Not enough info to give you my opinion based on a long life and much study of the subject.
But:
What is your price range?
What is this gun for?
If for it is for defense, what is your life worth? (See first question)
Is it for your night stand or concealed carry?
If both it will be a compromise gun.
Are there children in the house?
(It is easier to disable a auto for safety than a revolver. See below)
A general rule: if you are not going to become very familiar with the gun by practice, avoid "self stuffers".
They are more complicated and tend to have feed issues although people will sing the praises of their gun of choice.
A revolver will go bang for sure when you want it to.
If not, simply pull the trigger again.
Are you going to keep this gun the rest of your life. (I think that is a good practice. I've regreted selling most all guns I ever did sell).
A final rule of thumb.
Invest in quality.
You can't go wrong with a Colt or Kimber. Smith is an old line and has had bumps in the road. Be careful.
Go to a gun show for a big selection in one place and education.
Then pick your gun.

My daily carry is a Charger Arms undercover. Had it 30 years. Fits in my pants pocket.
"Why do you carry a 38, are you expecting trouble?"
"No, if I was expecting trouble, I would carry a 45"