The 75mm Summilux-M f/1.4 is a legendary lens, and it only became more legendary when it discontinued.

The 75mm is recognized by the narrow depth of field wide open. Traditionally 90mm and 75mm lenses have been considered good portrait lenses, most likely because one can isolate the subject from the background. With a tele you isolate the backgrpund with a more narrow angle, and the backgrund appears more solid or flat (whereas a wide angle includes more of the background due to a wider angle, and the backgrpund appears with more details and more distance between them).