I don`t think it makes so much difference landing into ICN where you sit. The airport is far away from the city. Mostly planes land out of the south, meaning you have on the left hand side (mostly) seaviews and on the right hand side landviews. On taking off at HKG there is a chance you will fly over the city, in that case the right hand side is better, if you however turn away from Lantau there will be some views on the left again... (depending on when your flight leaves and the weather).

Upon arrival into HKG. It`s either seaview on both sides or some skyline views on the left upon approach.

so take your pick.