@Mr.OneShot
You've touched on one of my favorite topics.
It's all in what your needs are-field use, concealed carry, range, what have you. Most people here are interested in concealed carry so I'm going to address that area.
My personal preference for a CC holster is inside the waistband or IWB. IWB carry takes some getting used to, but when you adapt to it, it is easy to conceal a pistol with a waist length or longer jacket or just a shirt tail hanging out. The draw motion is smooth and easy.
My personal best CC IWB holster is the Texas Heritage from Tucker.
http://tuckergunleather.com/teheiwb.htmlIt is comfortable as it is made of leather and does not have a reinforced mouth. Some think a reinforced mouth is a necessity so that one can re-holster quickly. My thinking is the primary consideration is to be able to draw and put the pistol into action quickly. You can take your time when re-holstering once you have brought the situation back to where it needs to be.
However, if you feel you must have a holster with an open mouth, look at Garrett Industries Silent Thunder.
http://garrettindustries.mybigcommerce.com/products/Silent-Thunder-IWB.htmlGarrett uses a proprietary process to bond a leather lining to the interior surface of a kydex holster body. This has two big pluses-it protects your finish a bit better and it really makes the holster quiet.
I've been carrying concealed on a daily basis for over 3 decades. I have used a variety of holsters over these years-various manufacturers, various styles from IWB, hip, shoulder, ankle, and butt/belly pack. For me, IWB is the best method of concealed carry. These holsters are ones I personally own and use. Both companies are great to deal with. And both of these holsters give you the option to carry in "tuckable" fashion, with your shirt tucked in your waistband over the holster to conceal the firearm. Not an option I use, especially with the PX4 due to its size, but it is an option. And, seeing as you're in SC, an option you might want to consider as your heat and humidity are a bit higher than here in Michigan.