Favorite aspect of 4x games

[AgentZero]

I like the exploration, and building my own little economic empire. Hell, sometimes I play 4X games with the AIs turned off, just so I can happily go about exploring the galaxy, developing new colonies and discovering new technologies, without really worrying about being competitive, spending every spare unit of resource building warships and fighters and troops to get ready for the inevitable onslaught of mindless drones bent on my destruction.