I like holsters with body shields. The shield extends upward between the gun and your body and offers significant advantages: it makes for easy reholstering; it helps to keep shirts from being pushed down into the holster; and it protects the gun from body oils, sweat and salt.

Body shields also provide an additional advantage for guns with external safeties, helping prevent the safety from being deactivated accidentally by rubbing against the body.

There is no exact formula for putting all of these elements together. What is comfortable for one person may not be for another. Unfortunately, it's a trial-and-error situation. The good news is that many quality holster manufacturers accept returns if you are not satisfied. It's worth buying from those companies just for that opportunity, even if you have to pay a little more.