Codex $100 or grok $100 for langgraph/langchain development?

An AI Engineer is seeking advice on whether to choose a $100/month Codex or Grok plan for heavy coding, primarily in Python, LangGraph/LangChain, LLM agents, evals, and backend services. The user found Grok to be fast but noted that Codex "looks smarter." They are looking for recommendations on the best plan for their development needs.

This post directly compares the practical experience and perceived intelligence of Codex and Grok for LangGraph/LangChain development, unlike typical feature-list comparisons.