35mm. It's more versatile. The 50mm is such an overrated lens not to mention not a good portrait lens.People's heads will get distorted when shot with the 50mm (unless you're going for the distorted head look).
I agree with Peteroc. Keep the 35mm and get either the 85mm or 135mm.
Are you saying the 35mm is better than the 50 for close portraits?
Personally, I think neither is good for that, use an 85mm or 135.
Bodies: 6D, EOS-M
Lenses: Rokinon 14mm 2.8, 50mm 1.4, 85mm 1.8, 100mm 2.8L IS Macro, 135mm 2.0L, 24-70mm 2.8L II, 70-200mm 2.8L IS II, EF-M 22 2.0, EF-M 18-55mm, Extender EF 2xIII; Speedlites: 600EX-RT(2x), 430EX II, 90EX