5. Behind the Scenes
I'm not going to rate this origin at this point because frankly, I wasn't able to experience it. I did start a game with it, but my tiny galaxy was too peaceful and nobody went to war with anyone in the first century so it did nothing and I stopped playing because I still had a lot of origins to try out. My advice for anyone looking to play the origin would be to make their galaxy one size larger than what they normally play and maybe activate the Starnet AI mod. The only reason I haven't done that was because I'm trying to play through as many origins as possible before the voting ends.
6. The Caretaker
This is an excellent origin that blends narrative with new gameplay options. I was impressed by just how extensive the origin is too. It features new buildings, jobs, planetary decisions, ship computers, ascension perks, and even a new planetary specialization. I particularly enjoyed the Caretaker giving me feedback on the ascension perks I was picking. First the approval for taking One Vision and the new origin specific APs, then later anger when I picked Xeno-Compatibility and Engineered Evolution, and finally seething rage when I went for Evolutionary Mastery.
The origin works well for a variety of different empires, depending on how friendly you want to be with the Caretaker. Xenophopic isolationists that eschew ascension in favor of megastructures are the best match for happily living under the Caretaker's enlightened guidance, while other types of empires make for good rebellious children.
I have nothing truly bad to say about the origin. The biggest flaw I found was that I was annoyed by the Ward jobs as I deemed them pretty useless and they prevented me from noticing when my planets had enough pops for more useful jobs. I would appreciate it if Ward jobs were something you have to specifically enable, perhaps with a planetary decision, rather than being automatically there. I also found some missing localization. But that's really about it and I feel like I'm really nitpicking.
I wanted to stop rating the origins because after thinking about it I decided it's a bit presumptuous for me to do so and most of them would get the same "good" rating anyway, but this is definitely the best origin I've tried so far so I am still going to rate it as 5/5 (excellent).
7. Fleet Overlords
The origin was an interesting experience, but ended up being less fun than I anticipated. It's not that the origin is bad though. Instead it only exposed underlying problems with the base game. You essentially skip the exploration phase (because you have 3 federation buddies that explore the galaxy for you and can only ever control a single star system anyway), you don't have any planets to manage, and you always have a CB to force empires to join your federation. All this leaves you with nothing to do except gobble up the AI empires one by one. It's a bit of a challenge early on when your federation members only pay you 10% tax, but once you can increases taxes to 20% it become pretty much smooth sailing for the rest of the game. It's all kind of dull, really.
The problem with the origin is really a problem of the core game and how warfare isn't all that exciting by itself. The most succinct way of describing it that I can think of is that it instantly catapults you into the late mid-game, just without the micro to keep you busy. I don't have any advice for the author because frankly there is little the author can do to improve the situation by editing the origin. What would actually be needed to make the origin better is an overhaul of the entire warfare side of the game.
But that doesn't mean that you shouldn't play it. Quite the contrary! As I wrote at the very start it was an interesting experience and I would recommend playing the origin to anyone who wants to acquire a deeper understanding of Stellaris' game design and have discussions about the warfare system and how to improve it. And it's impressive how radically the author was able to change gameplay too.