In terms of a prime lens on a full frame camera my preferred lens is the Nikon 105mm f2 DC. It provides a better working distance than the 85mm and it is still short enough to be easily used indoors. I dislike the 85mm when I was using a crop camera that turned it into a 135mm focal length as indoors it was often too long. Outdoors I use the 24-70mm and the 70-200mm zooms.
It seems that few people think of the 70-200mm f2.8 as a portrait or people lens but it is in fact excellent for this purpose. Nice bokeh and blurred out backgrounds thanks to the shallower DOF with the longer focal length. A 50mm lens may need f2 for shallow DOF but at 150-200mm a smaller aperture can be used to the same effect.
An excellent Nikon lens is the 24-105mm f4 IS lens but it is too slow for general wedding photography during the ceremony or reception. I rented one and used it for 15 minutes during a reception and took it off as it was too slow for the available light. With low light my cameras need f2.8 glass to focus fast enough to catch the shots with proper framing. Outdoors the 24-105mm is not as good a choice as the 70-200mm lens.
I would not bother with the 70-200mm f4 lens as it is not fast enough for use in photographing wedding ceremonies or receptions 100% of the time whereas the f2.8 version is fast enough even in dimly lit churches, which seems to be the rule, and candle lit receptions which are also commonplace.
With both weddings and engagement sessions one needs to be taking pictures and not frequently changing lenses. With two cameras during the bridal prep I will have the 105mm on one camera and the 24-70mm on the other and I do not need to make a lens change. I have the option of switching out the 24-70mm for a 14-24mm 2.8 lens (or with Canon I used the much less sharp 16-35mm f2.
for broader environmental shots during the prep, ceremony, and reception. For engagement shoots the 24-70mm and the 70-200mm are all that is needed if used properly with care as to the backgrounds, shooting angles, and apertures used.
If in doubt about the usefulness of a particular lens it pays to rent one for a week and try it out. It is inexpensive to do this and you avoid the risk of having something you will seldom use and end up selling at a loss in a year's time.
I can get all the shots my clients want with the 16mm fisheye, 24-70mm f2.8, 70-200mm f2.8, and a +4 Closeup lens that I use on both zooms. I used to carry along a macro lens and 35mm, 50mm, 85mm, and 105mm primes. The primes were completely unnecessary and more of a crutch than must have lenses with today's cameras. 10 years ago f1.4 primes were essential but the autofocus and high ISO capabilities of DSLR's has greatly improved since that time.