The closest alternative to Nano Banana 2 (Gemini 3.1 Flash Image Preview) is Gemini 3.6 Flash — comparable intelligence (50.1 vs —); for a cheaper option, GPT-5.6 Luna runs $0.100/M vs $0.500/M; and the best open-weight substitute is Kimi K3.
Gemini 3.6 Flash is the closest alternative to Nano Banana 2 (Gemini 3.1 Flash Image Preview), with an Intelligence Index of 50.1 (Nano Banana 2 (Gemini 3.1 Flash Image Preview) scores —) at $1.50 per million input tokens.
Yes — GPT-5.6 Luna costs $0.100 per million input tokens versus $0.500 for Nano Banana 2 (Gemini 3.1 Flash Image Preview), while staying within ~8 points of its Intelligence Index.
Kimi K3 is the strongest open-weight alternative to Nano Banana 2 (Gemini 3.1 Flash Image Preview) — downloadable from Hugging Face and self-hostable, scoring 57.1 on intelligence.