MOO2 is pure love. Have you tried Alpha Centauri? Only other strategy game to rival MOO2 for me.
I do, and actually played it not long ago, but the graphics seem to have aged badly for me in a way that MOO2s didn't. I can't even begin to say why.
I rather like Endless Legends from the new generation.
I tried a couple times and bounced. Odd, because I thought Endless Space was okay.
I'd hesitate to say the number of hours I've put into that game. Its probably alarming.War of the Chosen is pretty good too.