If you shoot landscapes, I'm surprised nobody has mentioned a Century graphic. I use one for landscapes and handheld stuff too. It has a graflock back and is compatible with RB67 backs, I use mine with roll film backs in 6X7, but you can get roll film backs for 6X4.5 to 6X9. It folds up to about 6" square by 2" thick. It has limited movements, rise, shift, drop, swing. It's totally non-electronic so a handheld meter is a must. It will handle lenses from 47 to about 160mm, longer with a telephoto lens type. Focusing is by rangefinder, ground glass, or scale. In a lot of ways, it's more versatile than an SLR. You can carry different backs for different negative sizes and types of film, and it has a shutter that doesn't sound like a gunshot going off. I have a Pentacon Six which has one of the quietest shutters of medium format SLRs, and compared to the Compur Shutter on my Century Graphic, the Pentacon sounds loud.
The Century Graphic is often referred to as the "Poor man's Linhoff" Just my .02.