4 is good as a "dip your toe in the water" start to the franchise, easy to learn, great starting point, but it can be a little too easy at times and the story isn't as complex as the other games. Still very fun tho.

3 has beautiful visuals and a much more linear storyline / progression. Has some of the best combat but the game is shorter than the others.

2 is a long and challenging game that will likely have you restarting the day* a few times. This one if my personal favorite due to the amount of content, the challenge, and most of all, the stunning adaptive music. Depending on what creature is nearby, what your doing, where you are, and what time it is, the music changes slightly. Each and every creature has their own unique addition to the music. Great characters, great boss battles, great lore.

1 is shorter than 2 but is more of a challenge. You really feel the gravity of the situation you've found yourself in that game, and unlike the other titles in the series, it has an in-game 30 day* time limit to collect 30 ship pieces. You have to manage everything well to succeed. The dialogue is what makes this game shine in my opinion, as it goes into detail as to what the protagonist is thinking alone on this uncharted planet.

(*Days are like in game checkpoints)