Metroid Prime 1 may have been a masterpiece, but in my opinion, Prime 2 took nearly all that made Prime 1 good, and improved it even further. However, there are some flaws to it that in the eyes of others keep it from outshining its predecessor.
Moon Studios had a gargantuan task, following up their first game, but they did so in style. The second Ori game is just as fantastic as the first, bringing in new mechanics, while keeping the feeling of playing as Ori alive.
By far the best experience I have had with any indie game to date. The art direction, the soundtrack and the gameplay merge together perfectly into this masterpiece of a game.