There's a mod that's called "Randy and Cassandra". It gives you a new storyteller which is basically Randy and Cassandra at the same time. You will get twice as many events since you are running 2 storytellers, but the chaos can be fun.
It's not really the difficulty that bothers me. Randy gets boring when he decides not to do anything for an entire year. I prefer regular attacks/disasters with a bit of downtime in between.
Randy is the only one that ever really gives me a good time. The others are too structured. Like, to the point with how much I've played I can easily predict what they will throw at me next. Randy, being totally random, keeps me on my toes.
Randy is too easy for me mid-game. Cassandra I got a bunch of difficult raids together with a nuclear winter as well as a cold snap that I barely survived.
With Randy I get a raid every now and then and a bunch of non-useful traders. On the same difficulty it is really too easy and doesn't allow me to grow my colony through captures as readily.
That's what Cassandra does, she will find a way to destroy you. She doesn't destroy gameplay, but the odds of survival. So you have to hurry and get that ship moving because sticking around getting wealthier means the end of your colony. Randy just leaves it to luck.
And for the record, with late game I mean at least 15 years
Randy or Cassandra. I've actually never played with Phoebe, but it seems to have the least exciting difficulty curve.
Randy will hit you with chaos but occasionally you'll be showered with help, truly feels random. The difficulty still scales by colony wealth so it's manageable and it prevents me from over extending myself. It also feels more realistic that as your colony grows it'll attract more
Cassandra is good, but it feels a little more "on the rails" and I don't find myself in as dire of situations. I'll usually go with her if I'm trying to experiment more on the run.
Perry Persistent I guess. I don't really rate any storyteller that highly. Winston Waves is kinda cool but the threat scale isn't balanced that well IMO.