having had a tour on Sunday, I would avoid 50B and 50J.
they sort of reach into the stairwell upstairs, feel very exposed / stand-alone and are right in front of the toilet so imagine that that's where people natrually wait if the toilets are in use.
53A - as discussed - looks like a good "new 62A" though the curving ceiling does require a bit of 'head down' bending.