Large APS-C (22.3 x 14.9 mm) sensor
Large sensors provide shallower depth of field and a nice blurry background for your portrait shots. Very High Resolution Sensor: 24.0MP
Canon M6's 24.0MP sensor will provide larger room for cropping, and you will be able print your portrait shots larger with more fine detail.
Good handling and existence of well placed physical controls on the camera body is very important during portrait shooting. It is faster and more intuitive to change the camera settings with dedicated buttons and knobs instead delving into the menus on the LCD.
No Image Stabilization
Due to the lack of sensor based Image stabilization, Canon M6 users have to rely on lenses with optical IS in order to maximize the sharpness of their handheld portrait shots. Currently there are native Canon EF-M mount lenses with Image Stabilization for Canon M6.