I feel happy with the following MF lenses on the a7R: 20 mm f/2.8, 28mm f/2.8, 55 mm f/2.8, 105 mm f/2.8, 180 mm f/2.8, and the 300 mm. All of these are the older AIS lenses of Nikon. This provides sufficient span of focal lengths; however, I do miss autofocus and image stabilization. To compensate the loss of image stabilization, I use an ISO from 200-800 and so far this has allowed me to keep the shutter speed fast enough for handholding the longer lenses. The main thing I miss is the autofocus, but thanks to the depth of field scale, I set the 20 mm to its hyperfocal distance and at f/11, everything from infinity to 2.5 feet is pretty sharp. Once I start using the 180 mm or higher telephoto, I mount the camera on a tripod.
I miss the convenience of a zoom, but I feel I have gained in image sharpness. For what it is worth, I feel the 28-70 mm kit zooms for the a7 does not measure up to the single focal length Nikon lenses. I sure hope the Zeiss 24-70mm provides fantastic optical performance.