Insulated or non-insulated -- it all depends on various factors, including:
- Is the garage attached to the house, and is the rest of the garage insulated?
- Are there rooms above the garage?
- Will the garage get direct sunlight? If so, will it heat up the door and transfer heat to the garage and the rest of the house?
- How important is having a quiet door to you? If you want it to be quiet, you'll probably want a steelback insulated door, since non-insulated doors tend to rattle as they go up and down in the track.