The latest models from Anthropic (Opus 4.6) and OpenAI (Codex 5.3) represent two distinct engineering methodologies. Opus is an autonomous agent you delegate to, while Codex is an interactive collaborator you pair-program with. Choosing a model is now a workflow decision, not just a performance one.

Beyond raw capability, top AI models exhibit distinct personalities. Ethan Mollick describes Anthropic's Claude as a fussy but strong "intellectual writer," ChatGPT as having friendly "conversational" and powerful "logical" modes, and Google's Gemini as a "neurotic" but smart model that can be self-deprecating.

While OpenAI and Google position their AIs as neutral tools (ChatGPT, Gemini), Anthropic is building a distinct brand by personifying its model as 'Claude.' This throwback to named assistants like Siri and Alexa creates a more personal user relationship, which could be a key differentiator in the consumer AI market.

While ChatGPT and Gemini chase mass adoption, Claude focuses on a "hyper-technical" user base. Features like Artifacts and Skills, while too complex for casual consumers, create a deep moat with engineers and prosumers who are willing to invest time in building complex workflows.

Anthropic is positioning itself as the "Apple" of AI: tasteful, opinionated, and focused on prosumer/enterprise users. In contrast, OpenAI is the "Microsoft": populist and broadly appealing, creating a familiar competitive dynamic that suggests future product and marketing strategies.

While ChatGPT has wider general usage, Claude is the preferred primary tool for the most engaged AI users. These users leverage AI for more hours, engage in more complex 'agentic' tasks, and report higher value gains, indicating Claude's strength with the advanced builder/practitioner segment.

OpenAI's GPT-5.1 update heavily focuses on making the model "warmer," more empathetic, and more conversational. This strategic emphasis on tone and personality signals that the competitive frontier for AI assistants is shifting from pure technical prowess to the quality of the user's emotional and conversational experience.

As models mature, their core differentiator will become their underlying personality and values, shaped by their creators' objective functions. One model might optimize for user productivity by being concise, while another optimizes for engagement by being verbose.

A key design difference separates leading chatbots. ChatGPT consistently ends responses with prompts for further interaction, an engagement-maximizing strategy. In contrast, Claude may challenge a user's line of questioning or even end a conversation if it deems it unproductive, reflecting an alternative optimization metric centered on user well-being.