Short comparison between GalCiv/MoO2 and Starfleet Command is.... apples and oranges.
GC and all the version of MOO are strategic empire-building games: the player works on expansion, tech and economic development, and warfare.
SFC (in all its versions) are detailed tactical battle games with a thin strategic wrapper. You command at most a small squadron of ships. The economic and technological development of your empire is completely beyond your control. The movement and actions of ships other than your squadron's are completely outside your control.
None of which makes any of these titles inherently good or bad. The SFC series are, in fact, darned *good* tactical battle games. But they're really not at all similar to GalCiv or MoO.