Claude 3 Opus

The first model from anyone that people openly preferred to GPT-4, and for most of 2024 the most expensive thing you could call from a terminal. It was retired with an unusual undertaking attached: Anthropic committed to keeping its weights, which is not the same as keeping the model running, but is more than anyone had promised before.

It wrote more than it strictly needed to, and the surplus was usually the good part.