For simplicity and ease of use a revolver is hard to beat. A 4" medium frame .357/38 would be a very good choice in my opinion. Specifically a Ruger GP 100 would be my choice. An S&W 686 is also a fine choice. Loaded with quality +P .38 rounds with a speed loader or two at hand and you're good to go.
If you're comfortable with a semiauto then your options are many. There are many 9mm, .40, and .45 acp (among others) to chose from.
"Any fool can criticize, condemn and complain and most fools do." Benjamin Franklin