I would say 35, but if you do not have any wider lens, 35 is not wide enough, with time photographers start appreciating wide lenses. In this case, 24-70 gives you not only flexibility, but also a wider lens, 34 on full frame is a focal lens to have.
35 is not that different from the 50, Both are general purpose walk around lenses. If you buy the 35, then consider also a 20 or a 24... You cannot have all the lenses you have and owning no wide lens!