There aren't many to choose from.
Nikon is a little different than Leica and even Soviet-era cameras. Nikon RF cameras and lenses were in serious producton for just 11 or 12 years and were only really popular for about 8 years before the Nikon F was introduced.
With very few exceptions, Nippon Kogaku developed one optical formula for each focal length/aperature. So, for example, there are a few hundred 5cm f/1.5 lenses from 1950 before the 5cm f/1.4 was introduced in late 1950, and the formula was unchanged for the 100,000 or so lenses sold up through 1963, when the formula was changed for 2,000 special-edition lenses sold with special-edition "Olympic" S3s.
The 1.5 lens and the Olympic lens are collectors editions that never see regular photographic use. So that 5cm f.14 is THE normal lens for a Nikon user.
The only alternative is a 5cm f/2 lens. This optical formula was completely unchanged thoughout its production life, though there are some variants in the barrel design. It has a magnificent reputation and a reputation for better out-of-focus areas than its faster sibling But 1.4 tends to be preferred by users beause of the extra f/stop. Both are outstandingly sharp. Contax and Kiev lenses fit the Nikon mount though there can be some focusing issues. However, anyone who owns a Nikkor 50mm isn't going to see any real difference with a Sonnar. The Nikkors had at least equal in sharpness, had better flare control, outstanding coatings and comparable out-of-focus characteristics. Zeiss insisted Nikkors were just copies of the Sonnar. Most users, including the staff of Life magazine, considered the Nikkors to be an improvement over the Sonnar design. Nikon published all its optical formulas as part of its advertising, so it wasn't trying to hide anything from Zeiss.
There was a 50mm f/3.5 macro released in Nikon RF mount. Intended for copy work, it is computed to be sharper than film emulsions of the era and to have a flat field of focus. It's not easy to do copy work with an RF, so not a lot of these were sold until the lens was reintroduced in SLR mount. Today, the RF version is considered to be quite collectible.
