Summary: This game gets an 8 from me out of the sheer ballsyness of scope that it plays at. You go from, "Look we have ion drives!" to, "Hold on a sec, I'ma make that star into a power factory for my civ, Brb." Woah! Mind blown. Warning though, it's complex and very arcane.
Summary: I was introduced to Space Empires III back in college, and I have been hooked ever since. It's easy to learn and fun to play, even for people who don't normally like strategy games (like me). SE5 ups the playability with newer and better graphics and more tech trees.
Summary: Without doubt, in my opinion the best of it's kind in this genre, and I have played many. The graphics are superb, very detailed main window includes animated planets and anomalies which looks great. Very helpful pop-ups appear when you mouse over anything on the screen.
Summary: As an avid SE4 player I was looking forward to this game, however the game has gone from a cleanly designed intuitive game to micromanagement hell. The interface is horrible and getting even basic information about your ships or planets requires multiple clicks through several menus.
Summary: One of the deepest 4X games around. Extensive research trees, challanging AI and detailed racial/unit/ship design. Modability is massive, with a thriving active community. From previous experience with the series, any remaining bugs will be found and patched over time.