Best Mods To Get?

[DarkStar]

I'm thinking about getting SE4 (been thinking along time, LOL). I'm still trying to figure if SE4 is worth $40. I played the demo but 100 turns can only tell you so much. People here seem to really like the add on mods. Can you tell me which mods are the best to get? If some of you would share why you like SE4 so much that would be great, I have a limited amount of cash to spend on games and much look at each purchase very close. Thanks in advance.