90% of the time I use my DeSantis E1 IWB leather holster made specifically for the G27/G27 models. Its super slim....sleek....and sturdy specially the stitching around the belt clip.
Provides a nice deep concealment but good enough to where the G26 magazine extension sticks out just enough to get a decent purchase on it when drawing.
When carrying OWB which is rare, mainly on my outdoor range trips, I use the hard plastic Glock 26/27 brand holster. Provides a nice snug fit, super simple and super cheap....