I tested Nano Banana 2.1 against ChatGPT, and it was close

Google upgraded its Nano Banana AI image generator to version 2.1 within Gemini, aiming to improve detail, instruction-following, and consistency. A side-by-side test against OpenAI's ChatGPT Images 2.5 showed both produce high-quality, photorealistic images with different artistic styles, indicating a close competition in AI image generation capabilities.