I haven't played much of Galaxy yet, actually, though I love what I have played. I didn't get around to trying out Sunshine until a year or two ago. At first I didn't care for it much, but it grew on me and I was very satisfied with the whole game by the end. So it's a tough call, each game has its merits. Not going to vote in the poll for now.
Open worlds are overrated, in my opinion. Sometimes a game is pretty linear but has the illusion of an open world. Sometimes a game is very open but has the illusion of linearity. I believe that Galaxy is hardly any less "open" than Sunshine. Both have a hubworld. Both have a number of "areas" where the brunt of the game takes place and which open up progressively as you play. Sunshine requires you to complete the first 7 missions of each area, whereas in Galaxy you merely have to complete I think 60 missions total from any areas in any order. Both games have "bonus" areas where you can collect additional Shines/Stars; in Sunshine, these will count towards "total completion," but will not help you progress through the story as they will in Galaxy.
