The closest alternative to GPT-3.5 Turbo 16k is GPT Chat Latest — comparable intelligence (— vs —); for a cheaper option, GPT-5.4 runs $2.50/M vs $3.00/M; for more speed, Morph V3 Large hits 2.6k t/s; and the best open-weight substitute is MiniMax M3.
GPT Chat Latest is the closest alternative to GPT-3.5 Turbo 16k, with an Intelligence Index of — (GPT-3.5 Turbo 16k scores —) at $5.00 per million input tokens.
Yes — GPT-5.4 costs $2.50 per million input tokens versus $3.00 for GPT-3.5 Turbo 16k, while staying within ~8 points of its Intelligence Index.
MiniMax M3 is the strongest open-weight alternative to GPT-3.5 Turbo 16k — downloadable from Hugging Face and self-hostable, scoring 54.7 on intelligence.