How are you defining 'best'?
There are quite a lot of lenses that will resolve finer detail than film can capture. Anything over 100 lp/mm will be aleatory, depending on the location and flatness of the film.
Once you go outside resolution figures, you can define 'best' in a dozen different ways. One Zeiss lens designer of my acquaintace reckoned that he had five different Zeiss 50mm lenses, each of which was 'best' for a particular application. Hell, I like my 58/2 Biotar for romantic colour; I loved the 58/1.4 Nikkor for 'roundness' and a three-dimensional look in black and white; the 50/2 Jupiter-8 has a lovely 'glow' to it; and I sold my 50/2 Summicron, sharper than any of that lot, because I almost never used it. If I could afford it, I'd buy a 50/1 Noctilux (a kind friend lent me one for a year) and I still use my 50/1.2 Canon for some shots: it's superb at f/4 to f/11, and, well, romantic at f/1.2.
My current favourite is probably the 50/2.5 Color-Skopar because it's so compact.