Gemini 3 vs. Claude Opus 4.5 vs. GPT-5.1 Codex: Which AI Model is the Best Designer?

3 Dec 2025. The era of AI-driven design is no longer a futuristic fantasy; it’s our present. Today, we pit three titans of generative AI – Google's Gemini 3, Anthropic's Claude Opus 4.5, and OpenAI's GPT-5.1 Codex – against each other in a real-world design challenge. The goal? Redesign the user interface (UI) of a hypothetical mobile banking application. This isn't just a theoretical exercise; it’s about understanding the practical capabilities, limitations, and nuances of each model in a domain demanding creativity, precision, and user empathy.

The Design Brief: Mobile Banking App Redesign

The brief was intentionally broad to allow each AI model to showcase its interpretative and creative abilities. We provided the following high-level instructions:

• Target Audience: Tech-savvy millennials and Gen Z.
• Core Functionality: Account management, money transfers, bill payments, investment tracking, and fraud detection.
• Aesthetic Guidelines: Modern, minimalist design with a focus on intuitive navigation and data visualization.
• Technical Constraints: The design should be easily implementable using React Native.
• Desired Outcome: A high-fidelity UI prototype (mockups and code snippets) along with a rationale behind design choices.

Each AI model received the exact same prompt. The results were, to say the least, illuminating.

Round 1: Understanding & Interpretation

This initial phase assessed the models' ability to parse the design brief and identify key requirements.

• Gemini 3: Showed a strong understanding of the target audience, prioritizing mobile-first design principles and gamified financial literacy tools. However, its initial interpretation of "minimalist design" leaned towards being overly simplistic, almost to the point of sacrificing functionality.
• Claude Opus 4.5: Impressed with its ability to proactively ask clarifying questions. It sought further details on user flows, specific features, and branding guidelines. This proactive approach demonstrated a deeper level of understanding and a commitment to creating a well-informed design.
• GPT-5.1 Codex: While technically proficient, Codex exhibited a more rigid interpretation of the brief. It delivered a functional design, but lacked the nuanced understanding of user psychology and aesthetic trends demonstrated by the other models.

Technical Insight: Claude Opus 4.5's proactive questioning highlights the importance of incorporating feedback loops into AI-driven design processes. Allowing models to ask clarifying questions leads to significantly better outcomes.

Round 2: Design Generation & Implementation

This phase focused on the actual design output – mockups, code snippets, and the overall usability of the proposed UI.

• Gemini 3: Generated aesthetically pleasing mockups with a clean, modern interface. Its use of motion graphics and micro-interactions was particularly noteworthy. However, the React Native code it produced was often incomplete and contained errors. Debugging and refinement required significant manual intervention.

  javascriptCopy
  1// Example React Native component generated by Gemini 3 (with errors)
  2import React from 'react';
  3import { View, Text, StyleSheet } from 'react-native';
  4
  5const AccountSummary = () => {
  6  return (
  7    <View style={styles.container}>
  8      <Text style={styles.balance}>Balance: {user.balance}</Text> // Error: user is undefined
  9    </View>
  10  );
  11};
  12
  13const styles = StyleSheet.create({
  14  container: {
  15    padding: 20,
  16    backgroundColor: '#f0f0f0',
  17  },
  18  balance: {
  19    fontSize: 20,
  20    fontWeight: 'bold',
  21  },
  22});
  23
  24export default AccountSummary;

  Practical Consideration: While Gemini 3 excels at visual design, its code generation capabilities are still maturing. Human oversight is crucial to ensure the accuracy and completeness of the generated code.

• Claude Opus 4.5: Delivered a well-structured UI prototype with a focus on usability and accessibility. Its designs were not as visually striking as Gemini 3's, but they were significantly more practical and user-friendly. The React Native code it generated was clean, well-documented, and largely error-free.

  javascriptCopy
  1// Example React Native component generated by Claude Opus 4.5 (functional and clean)
  2import React from 'react';
  3import { View, Text, StyleSheet } from 'react-native';
  4
  5const AccountSummary = ({ balance }) => {
  6  return (
  7    <View style={styles.container}>
  8      <Text style={styles.balance}>Balance: ${balance.toFixed(2)}</Text>
  9    </View>
  10  );
  11};
  12
  13const styles = StyleSheet.create({
  14  container: {
  15    padding: 20,
  16    backgroundColor: '#f0f0f0',
  17  },
  18  balance: {
  19    fontSize: 20,
  20    fontWeight: 'bold',
  21  },
  22});
  23
  24export default AccountSummary;

  Technical Depth: Claude Opus 4.5's code generation proficiency stems from its strong grounding in software engineering principles and its ability to leverage real-world code repositories for inspiration.

• GPT-5.1 Codex: Prioritized technical accuracy over aesthetic appeal. Its designs were functional and efficient, but lacked the visual flair necessary to resonate with the target audience. The generated code was highly optimized for performance, but difficult to understand and maintain.

  Innovation Highlight: Codex introduced a novel approach to fraud detection visualization, using a dynamic force-directed graph to represent suspicious transactions in real-time. While innovative, this feature required significant customization and optimization to be practically deployable.

Round 3: User Experience (UX) & Innovation

This final round evaluated the overall user experience of the designs, including intuitiveness, accessibility, and innovative features.

• Gemini 3: Struggled to balance aesthetic appeal with usability. The design, while visually stunning, was often cluttered and difficult to navigate. The gamified financial literacy tools felt forced and lacked a clear purpose.
• Claude Opus 4.5: Excelled at creating a seamless and intuitive user experience. The navigation was clear and logical, the information architecture was well-organized, and the accessibility features were thoughtfully implemented. The design prioritized user needs above all else.
• GPT-5.1 Codex: While its fraud detection visualization was innovative, the overall UX was hampered by its utilitarian design. The interface felt cold and impersonal, lacking the human touch necessary to build trust and engagement.

The Verdict: And the Winner Is...

Claude Opus 4.5 emerges as the clear winner. While Gemini 3 excelled at visual design and GPT-5.1 Codex demonstrated technical proficiency, Claude Opus 4.5 distinguished itself through its proactive approach, its focus on usability, and its ability to generate clean, functional code.

This result highlights a critical shift in the AI landscape. It's no longer enough for AI models to simply generate aesthetically pleasing designs or technically sound code. The true value lies in their ability to understand user needs, create intuitive experiences, and seamlessly integrate into existing development workflows.

Actionable Takeaways

• Prioritize User-Centric Design: Focus on understanding user needs and creating intuitive experiences. Don't sacrifice usability for aesthetics.
• Embrace Feedback Loops: Incorporate mechanisms for AI models to ask clarifying questions and receive feedback.
• Invest in Code Quality: Ensure that generated code is clean, well-documented, and easy to maintain.
• Don't Neglect Accessibility: Make sure your designs are accessible to users with disabilities.
• Human Oversight is Essential: AI-driven design is not a replacement for human designers; it's a powerful tool that can augment their capabilities.

The future of design is undoubtedly intertwined with AI. By understanding the strengths and weaknesses of different AI models, we can harness their power to create better, more user-friendly experiences for everyone.

Source

https://www.lennysnewsletter.com/p/which-ai-model-is-the-best-designer