Are any space sim action games good (RTS etc.)

I was in love with Ascendancy, a TBS, but the critics slammed it for mediocre AI.
Now I've been playing Space Empires IV, a great game all around, but aging.  I saw one critic disrespect the AI, but I think it was a fool. There are three difficulty levels that vary widely.  I've seen mature opposition at the medium level have not tried the top difficulty yet. He didn't mention these and I think his comments were merely to promote his own mod.
I've played Homeworld and Sins of a Solar Empire.  Sins of a Solar Empire seemed unorganized to me.  I could almost get into Homeworld but am also interested in what else might be good in space RTS.  I'll have another go at Homeworld in the meantime...
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Cursed to be walking in the shadows of death