Well, the closest thing I can come to in my book is right now Stars in Shadow (so devs, keep up the good work), but what would your dream be?
My dream would be the following:
1. SiS when it comes to planeatary developments (easy and quick with many options) and some parts of the space battles.
2. More special weaponry (like mines area of effect weapons, maybe something like SiS version 2.0?) in the tactical battles.
3. Some sort of Hero option for special commanders like Age of Wonders 3.
4. Graphical battles (but still turn based) like Battle field Gothic: Armada (just love how these space battle look).
5. Real physics when it comes to inertia on the space ship and the like (I remember playing a board game like this but I cant remember the name).
6. More Civilization like when it comes to diplomacy and planet development.
7. Galactic Civilization 3 when it comes to customizing races/ships
So, combine all these games into a mega space game that would absoluely kill all other space games. So, what would you like to see?