From this list, I chose the 28/2 as I could see myself using that if I came upon the coin to do so. However I'd far rather see see a nice new collapsible Tessar 50/3.5 (!) instead.
This was, and remains, one of the greatest lens designs in photographic history and has a distinctive look unlike any other design. The 3.5 version is, historically, noticeably better than the 2.8 so I'd rather have it over the 1/2 stop of speed. Currently I am not aware of anyone making this classic design for our cameras - and yes, that includes the modern 50/2.8 Elmar. The Elmar is not quite a Tessar - that positioning of the aperture diaphragm really does have an impact on the overall drawing of the lens. This is a good thing for both Lieca and Zeiss fans as it gives both a distinctive look.
William