I think Royalty is a must have for me. Combat is a big part of the game and it improves it a lot.

Psycasts give you options beyond a big firing line. Ultra tech swords, hammers, shields, and much better armor make melee useful. With those combined you can play a tall colony instead of a wide colony.

It also adds more interesting reward quests.

After that ideology vs boitech is what interests you.

Ideology allows you to change what makes your pawns happy or sad and what they are good at. It also gives access to reverse ageing and fixing scars and missing parts.

Lots of role play with mechanics. So you can be transhumanist, mad max raiders, drug cults, or nature loving hippies.

Biotech adds child birth, genetics, genetic engineering, vampires, robots and pollution. The genetics are somewhat OP but fun. The robots ate kind of meh.

Pollution is a fun idea but implemented in a very dumb way. It's basicly stockpile this stuff until late game when you get a magic pollution destroying machine. I would like a mid game option that gives something to do with it even if it's complicated and time consuming.