I have two mounts.
First is a Brodit that clamps over the airvent in the dash and I use this everyday. It wasn't the cheapest, but works really great and is well designed - I can rotate into landscape for navigation without having to loosen anything and there is no vibration/shaking with it. The good thing about the Brodit mounts is that it comes in two parts. The first is a non-impacting mount point designed for the car and the second is a fitting for the phone. If you change the phone or the car... all you need to get is one new piece.
For travel I bought a generic expandable grip holder that mounts on the windscreen. The reason is because I use an otterbox commuter when travelling and is fits really well. The image is below, however I normally fit it so it rests on the dashboard as there is a slight shake from it.