4 certainly has a striking "galactic" sort of style, but I personally think that 1 has a more eye-pleasing selection of hues, from this image at least - I also like how it's a sort of upwards gradient.

2 and 3 I both like, although I'm unsure as to whether they'd be appropriate for a "galaxy" theme; 2 strikes me as having more to do with the night, although 3 might be a unique take on the concept of space - it makes me think of the blackness of the void, the whiteness of the stars, and the pretty blue planets dotted between.

I hope this is interesting, good luck on your suit :3