The best I know.
It is just the best (at least from the many I have tried). Agility excels at producing new articles, while Koala is ideal for rewriting content. Both have their advantages, and they way for personalisation. Koala is relatively easier to replace by a direct interaction with a good LLM. Agility is faster to configure. There are many good tools (and much more than aren't good at all). But Agility is the best.