It ultimately doesn't matter that much, but I've noticed I generally like building ships in the spaceplane hangar more than the VAB.

Its something about the cooler lighting and more open space, and you can move around the area to view more angles easier. Plus if your spacecraft is a plane or operates in the vacuum then youre likely gonna be seeing it from a horizontal angle more often, so it feels helpful.

Its trivial, but im curious if anyone else has similar preferences.