I'm a big fan of Wild Bill's Concealment's Covert Carry Holster.

Wild Bill's Concealment | The Professional's Choice

1) It's a tuckable design, so you can wear it with a dress shirt if you need to.

2) the clip is offset to the rear which gives it a lower profile and helps keep the butt tucked in tight. It also creates a wider surface area that helps comfort and stability.

3) Leather is far more comfortable than Kydex in hot or cold weather.

4) The mouth uses a double thickness of leather around an insert so the mouth stays open even in thew waist band with the pistol removed.

5) The single clip makes the holster easy to remove if you're shooting a striker fired pistol with no manual safety, so that you can insert it in the holster while visually observing that there is nothing obstructing the trigger.