I did 380 out to SIN and back on the 789 from KUL last weekend both flights in 1K. I enjoyed both flights are there were pluses and minuses to both.

On the 380 the seat has an enormous amount of space plus you can put your carry on in the seat wardrobe as it is also massive. I didn't get disturbed by the toilet just ahead of 1K but at the start and end of the flight was disturbed quite a bit by the crew accessing large storage cupboards under the stair case which open just by 1K.

Coming back on the 789 the seat seemed better thought out and I liked the new controller and thought the screen quality was excellent. I didn't mind that there is no longer a buddy seat and preferred that the screen is permanently deployed so you can watch during taxi and take off. The wardrobe at the seat is hardly big enough to hang a jacket so no chance of getting my bag in there.

The lack of a second toilet did however seem to be an issue although the crew were aware of it and went to see if a club toilet was free if they saw someone waiting. Not a great situation though. The other thing that did seem to be an issue was the lack of galley space to prep meals. I know the galleys are always small but the crew seemed to really struggle with the amount of space. They also mentioned that the coffee machine had been changed and they struggled with that as well! (They also admitted that they only seemed to have 1 espresso cup loaded!)

On both planes 1K felt very private but I think give the choice I would tend to the 380 to get more space and the additional wc!