All the 777 and 787 variants have lie flat seats in a pod with the 'cubicle' walls that you refer to. They also have the same dining options and very similar entertainment options.
When we peel back the onion, the 777-300 legacy premium seating (that's being replaced over the coming year) is very good compared to what's in the 777-200 fleet or 787-8 and 787-9 (not "P") fleets. The 787-9P is very good, especially if you get a bulkhead row.
I think other than the front row the legacy 777-200, 787-8, 787-9 non P, and 777-300 all have more comfortable J seats than the new 787P regular J seats--I found them to be tight and uncomfortably particularly in the footwells.