The value flagship of the GPT-5 line — most of 5.5's ability for less than half the price.
GPT-5.4 is the balanced GPT-5 model: most of the flagship's capability at roughly half the price and a bit faster. For day-to-day agent work it's the sweet spot in OpenAI's lineup, with the same 1M-token context as 5.5.
The OpenAI daily driver — strong and well-priced.
The model picks the moves; the agent runs the loop, the tools, and the guardrails. Once you've chosen a model, see which agent gets the most out of it.