I tested 9 flagships (Claude 4.6, GPT-5.2, Gemini 3.1 Pro, Kimi K2.5, etc.) in my own mini-benchmark with novel tasks, web search disabled and zero training contamination and no cheating possible.
TL;DR: Claude 4.6 is currently the best reasoning model, GPT-5.2 is overrated, and open-source is catching up fast, in particular Moonshot.ai’s Kimi K2.5 seems very capable.
You can easily use the link https://openrouter.ai/chat?models=anthropic%2Fclaude-opus-4.6%2Copenai%2Fgpt-5.2%2Cx-ai%2Fgrok-4.1-fast%2Cgoogle%2Fgemini-3.1-pro-preview%2Cz-ai%2Fglm-5%2Cminimax%2Fminimax-m2.5%2Cqwen%2Fqwen3.5-plus-02-15%2Cmoonshotai%2Fkimi-k2.5 to ask all flagship models this question in parallel. Personally I would definitely not leave my children alone with a priest (they might try to convert them), but if your constraint is only baby+candy, then in my test Gemini, GLM, Qwen and Kimi made that, and only that, assumption.