MH (Malaysia Airlines) seats have 34" pitch
If you have a CX gold card, go with CX. Think, you get CX lounge access with that during you departure and transit which will be nicer than the PP lounges (unlikely to have decent showers in the PP lounges. I think a shower during transit on such a long flight helps to revive you.) Decent duty free shopping at both HKG and SIN if you are so inclined.
Not sure why people think that being in Y on an A380 is an advantage. There are more Y pax waiting to check-in, board and get off the plane at each stop.