I have played sins diplomacy many times.  Nowadays i am playing Starshatter the gatehring storm (Space(cap and fighter) and ground combat(fighter) simulation). I have also played x2 :the threat and freelancer(rpg).

Starshatter the gathering storm (stgs) has third person control of caps and cockpit of fighters. It has a storyline with semi-dynamic campaign(fixed objectives with random missions).

On comparison with sins. Sins has colonization feature, realtime capital ship, carrier and frigate combat along with planetary bombardment and a random mission each time.

If you want to command a capship while sins, one must shift to stgs. No other space sim fills up this  blank. Bridge commander is rigidly fixed. Stgs offers mission making,which makes it better than bridgecommander. You may make your own campaign if some effort is made.

However, if you want to colonize new planets, stgs lack this feature completely. This is where sins shine beating almost every space sim except for freespace.

X2 and freelancer are extremely boring without a storyline.

Next space sim era must fill in these blanks. I dream of a FPS and third person game like X2, where you can follow millitary carrers in addition to freelancer like that simulated in starshatter. And like in sins one can also lead a colony cap ship fleet.

Any more great ideas?