I've been playing Star dock's titles for some years now. I first started with SoSE and Demigod, and later moved to Elemental: Fallen Enchantress and Legendary Heroes.
I've tried only one other space 4x Game and that is Endless space. I felt that the game felt rigid, traveling using space lanes in endless space felt really awkward in the sense there was no way to intercept ships without staying in orbit around a planet. Pirates felt horribly awkward often fielding more potent fleets than players in some circumstances.
The card based combat was absolutely horrid. There was a lot about the game that was unpleasant for me. Although i did get around 60 hours out of it before i decided that the game wasn't for me.
If someone could explain what makes the two series different that would be very helpful. I have quite a few friends that played GCII and told me to get it. Any help would be appreciated.
PS. List of 4x games I've played:
Civ 3, Civ 4, Civ 5, AoW II, Endless Space, SoSE, Elemental FE, Elemental LH, Eador MOBW, COE3, and a few others.