The closest alternative to Claude Opus 4.6 is Grok 4.3 — comparable intelligence (53.2 vs 52.9); for a cheaper option, GPT-5.4 runs $2.50/M vs $5.00/M; for more speed, MiniMax M2.7 hits 211 t/s; and the best open-weight substitute is MiniMax M3.
Grok 4.3 is the closest alternative to Claude Opus 4.6, with an Intelligence Index of 53.2 (Claude Opus 4.6 scores 52.9) at $1.25 per million input tokens.
Yes — GPT-5.4 costs $2.50 per million input tokens versus $5.00 for Claude Opus 4.6, while staying within ~8 points of its Intelligence Index.
MiniMax M3 is the strongest open-weight alternative to Claude Opus 4.6 — downloadable from Hugging Face and self-hostable, scoring 54.7 on intelligence.