The 777s have (IMHO) the most comfortable seats in Cloud Nine of the entire fleet. The are true lie-flat seats with very comfortable padding, good leg space and good shoulder room as well. I sleep well on these (although I also sleep just fine in Economy Class exit rows, so maybe not the best example!).

3KL are the pair by the window, so you don't have to deal with the awful middle seat.

There is a small difference between the seats on the older pair of 77Ws (ET-APX/APY) and the newer pair (ET-ASK/ASL), which is that the IFE has a larger screen on the latter. That aside, the seats are identical (as are the seats on the 77L should that be swapped for any reason).

I particularly enjoy the Cloud Nine catering that features BOTH the Ethiopian traditional selection as well as an international menu selection (yes, you are invited to and even EXPECTED to eat two main courses). If you don't know Ethiopian food, just ask the crew to make up a selection for you - they love doing that and explaining what pairs best with what. Like most African airlines, the bar is free flowing and they take genuine pleasure in ensuring your glass is always topped up.

ET may be nothing fancy, but I've never walked away from an ET Cloud Nine experience with a negative impression. The crew do everything they can to make your flight pleasant (in sharp contrast to many other more "premium" carriers) and that goes a long way towards creating a positive memory.