Originally posted by normhead AV mode is 98% of my shooting, since from my perspective, the thing that most affects how much I like my pictures is control of DoF. If I set the ISO and ƒ stop, I don't care if the camera sets the shutter speed. But also check out TAV mode, really cool, you set shutter speed and aperture, the camera sets the ISO. Great for moving subjects where you want to freeze the action.
I too place much importance on depth of field control and used to shoot almost exclusively in Av mode on my K-7. But I do lots of low light shooting, and sometimes the camera has to choose a really slow shutter speed, causing slight motion blur.
With the K-3, I now more commonly use TAv mode. I set the shutter speed just fast enough to avoid motion blur (typically 1/my lens focal length), then select aperture as appropriate for the desired DOF, and let the camera choose ISO. With the K-3 I dare to this because the noise performance is better than on the K-7.