Agrarian Idyll 12
Aristocratic Elite 12
Beacon of Liberty 11
Citizen Service 13
Corporate Dominion 14
Corvée System 10
Cutthroat Politics 13
Distinguished Admiralty 12
Efficient Bureaucracy 9
Environmentalist 13
Exalted Priesthood 10
Feudal Society 11
Free Haven 8
Functional Architecture 12
Idealistic Foundation 12
Imperial Cult 12
Inward Perfection 14
Meritocracy 12
Mining Guilds 20 (+1)
Nationalistic Zeal 10
Parliamentary System 12
Philosopher King 10
Police State 10
Shadow Council 12
Slaver Guilds 13
Warrior Culture 2 (-2)
Technocracy 13
Fanatic Purifiers 14
Mechanist 14
Syncretic Evolution 12
Life-Seeded 0 - Eliminated
Post-Apocalyptic 10
Barbaric Despoilers 9
Picking one to up was easy. Mining guilds is by far the best civic not just because of its power, but also because it is that good for absolutely everyone on account of having no requirements either in terms of government type, ethos, or playstyle. I feel like it should already have 30 points by now. There are other strong choices like Slaver Guilds, but it's no good if you don't play with slaves. Or Corporate Dominion, but it has fairly restrictive requirements. Cutthroat politics is really good, because edict cost reductions are rare, but it's not very useful early because you need the influence for expansion. There are certainly arguments to be made for what is number two, but the number one spot is indisputable.
Now, what is actually the very worst civics is a lot more interesting because it makes me consider things I haven't considered as closely before. There are a bunch of them that I have sorted into a pile labelled "never, ever pick unless for rp". But to what degree are they absolute garbage from a power level perspective? That life-seeded went first feels right because it's really the only one that actively makes you much worse. There are many others that I consider having no benefit at all, or at least negligible enough to not consider. Shadow Council is one of these, because I don't think it's worthwhile to spend influence on votes. Philosopher King because leaders gain experience so slowly that they'll probably die before it matters, and if you elect someone who is already at level 10 the retain the level despite the lower level cap. Corvée system because the cost of resettlement isn't very significant, but at the same time I've seen it used to make resettlement free which can be useful to get your colonies up and running faster at a time where the cost is not as insignificant. All of these, and others, do something though, so how do I pick which one is the absolute worst. I considered Barbaric Despoilers, because raiding is fairly useless and the diplomatic penalty is significant, but the tradition swap that is not in the description of the Civic is actually really good, so while I still think it's a bad pick I don't think it's the worst. I decided to crown Warrior Culture as the worst of the remaining choices because ground combat matters so little in the game. Just recruit a couple of extra armies for what is close to the same effect.