Avoid the EK B777s in economy with 10 across seating, it's like a sardine can. SQ, QATAR and a few others have 9 across which is much nicer.
Singapore Airlines would give you one stop instead of three, and with the number of flights ex LHR you could time your arrival for either minimum connection time in Changi or have a stop over of a few hours/days.
After fourteen hours in economy, a shower, change of clothes, decent meal, proper sleep, gym workout would make you feel human again.