Assuming the A380 isn't using the ancient old seats, the window seats are extremely private and you don't need to step over anyone to get out. If you're planning on sleeping I'd take that (unless you're taller than 6'2", in which case it's too short to sleep comfortably). If you're going to be awake the whole time, I'd definitely do the KE flight assuming a window seat is available.
Just be aware that KE tends to keep the cabin at a temperature that many find uncomfortably warm, so you may want to bring a USB powered fan.