I created these last night – all of them are very quick & dirty; it was, so to speak, an insignia brainstorming session.
A+B: I like these, but I feel they scream “Sweden in space”. That may be acceptable for a colony that was established for the Swedish, but I am not entirely sure I’d want it as a symbol for one of the interstellar nations. Still, a candidate for actual use.
C+D: Color variations. C is the Finnish version I guess.
E: Not too fond of this, perhaps it could be used for a corporation, very small nation or an individual colony.
F: I like this one. Perhaps for the Thousand Worlds nation.
G+H: I also like this one. Colors could be changed, and perhaps the entire thing could be on a circular background or something. Definitely a candidate for actual use.
J+K: Not too fond of these.
M: Turkic/Islamic feel to this symbol. Could be used – I don’t hate it – but it doesn’t have a cool factor.
N: Sword impaling a planet – planet obviously would need work. I kinda like it, need to see how this comes out.
O+P: Two slight variations; I prefer the aligned version (O) rather than the one with the stars at an angle. Again slightly Islamic/Turkic feel. Another candidate for actual use.
Here are some additional variants as suggested by Realmwright: