I voted for 50 although like others I too like the 40. (and 80mm on 6x7, 60mm on 645 in film days and now 20mm on my Panasonic GF1 and 28mm on the Nikon D300)
Ahhh, to have been in Paris in the 1960s a 35 Summicron on the M2, 50 'cron on the M3 ... running into Doisneau and HC-B from time to time... !
btw, a 35mm lens does not have "more depth of field" than a 50. DoF is a function of subject magnification, not focal length.
To get the same subject size w/ a 35 you need to move closer and when you do DoF is the same (although the perspective is different)
Yes, from equal distances the 35 has more DoF but the subject is smaller than with the 50. Back up the 50 until magnification is equal and, again, DoF will be same as the 35 .