I'd say a Wollensak Velostigmat Series II, which is an f/4.5 Tessar. And go for one with a diffusion ring at the front; it's a nice option to have, one that the other lenses don't have. Note that these often come in older Betax shutters that don't have flash synch, but you can add a synched Packard Shutter for studio strobe work.