AI Model Comparison Guide

This guide provides a comprehensive comparison of AI models available in Cursor and Claude Code, helping you choose the right model for your specific development tasks.

Model Overview

Primary Development Models (2025)

• Claude Sonnet 4.5: Best coding model in the world with 1M context - superior to Opus 4 for daily work (Anthropic announcement)
• Claude Opus 4: Premium model (5x cost) - still preferred by some for architectural planning
• gpt-5-codex: Excellent for bug fixing and UI generation (available in Cursor)
• Gemini 2.5 Pro: Best for extreme context scenarios (1M+ tokens)

Quick Selection Guide

By Task

Task Type	Recommended Model	Why
Daily coding	Claude Sonnet 4.5	Best coding model, 1M context, cost-effective
Bug fixing	gpt-5-codex	Specialized for bug fixes (Cursor)
UI generation	gpt-5-codex	Excellent for frontend work (Cursor)
Architecture & refactoring	Claude Sonnet 4.5	Superior reasoning and context
Large codebase analysis	Claude Sonnet 4.5	1M token context handles entire repos
Extreme context needs	Gemini 2.5 Pro	When you exceed 1M tokens
Complex planning	Claude Opus 4	Some prefer for architectural depth

By Cost

Budget	Primary Model	When to Upgrade
Standard	Claude Sonnet 4.5	Handles 95% of tasks
Plus	Sonnet 4.5 + gpt-5-codex	Add for bug fixing & UI work
Premium	Add Opus 4 when needed	For specific complex architecture
Enterprise	Add Gemini 2.5 Pro	When exceeding 1M token context

Detailed Model Specifications

Claude Models (Anthropic)

Model	Context Window	Strengths	Best For	Relative Cost
Claude Sonnet 4.5	1M	Best coding model, superior reasoning, agent building	All development tasks (95%+)	1x (baseline)
Claude Opus 4	200k	Deep reasoning, complex problem solving	Architecture design when Sonnet 4.5 isn’t enough	5x

Claude Sonnet 4.5 Deep Dive

Released: September 29, 2025 Notable: Best coding model in the world, better than Opus 4 for most tasks

Capabilities:

• 1 million token context window - analyze entire large codebases
• State-of-the-art on SWE-bench Verified evaluation
• Best at building complex agents and computer use
• Superior reasoning and mathematical capabilities
• Can maintain focus for 30+ hours on complex tasks
• Excellent at understanding large codebases
• Strong refactoring suggestions across many files
• Accurate bug detection

Why it’s better than Opus 4:

• Larger context window (1M vs 200k)
• Better at coding tasks
• Superior agent building capabilities
• Same cost as previous Sonnet ($3/$15 per million tokens)

Optimal Use Cases:

// Example: Large-scale refactoring with massive context
// Sonnet 4.5 can hold entire codebases in memory
// and understand cross-file dependencies
async function refactorEntireAuthSystem() {
  // Sonnet 4.5 excels at:
  // - Understanding all related files at once
  // - Complex multi-file refactoring
  // - Building sophisticated automation
  // - Long-running complex tasks
}

Claude Opus 4.1 Deep Dive

Capabilities:

• Unmatched architectural understanding
• Can design entire systems from requirements
• Excellent at finding subtle bugs
• Superior code review capabilities
• Best at understanding complex business logic

When to Upgrade to Opus 4.1:

1. Designing new system architecture
2. Solving bugs that stumped Sonnet 4
3. Complex multi-file refactoring
4. Performance optimization requiring deep analysis
5. Security audit and vulnerability detection

OpenAI Models (Cursor Only)

Model	Context Window	Strengths	Best For	Relative Cost
gpt-5-codex	200k	Specialized for bug fixing and UI generation	Bug fixes, frontend development	Premium

gpt-5-codex Deep Dive

Available in: Cursor only

What it’s good at:

• Bug fixing: Specialized training for identifying and fixing bugs
• UI generation: Excellent at creating and refining user interfaces
• Frontend development: Strong understanding of modern frontend frameworks

When to use:

• Debugging complex issues that are hard to trace
• Building or iterating on UI components
• Frontend-heavy features
• Quick bug fixes in production

Note: While gpt-5-codex is very good for bug fixing and UI work, Claude Sonnet 4.5 is still better for general daily development work due to its larger context window and superior overall coding capabilities.

Google Models

Model	Context Window	Strengths	Best For	Relative Cost
Gemini 2.5 Pro	1M	Massive context, good reasoning	When you exceed Sonnet 4.5’s 1M context	1.5x

Gemini 2.5 Pro Deep Dive

Unique Advantages:

• 1 million token context window
• Can analyze entire medium-sized codebases
• Excellent cross-file understanding
• Good at maintaining consistency

Optimal Scenarios:

1. Analyzing monorepos
2. Understanding legacy codebases
3. Cross-service dependency mapping
4. Large-scale refactoring planning

Model Selection Strategy

Model Capabilities

Claude Sonnet 4.5 - The Default Choice

Best For 95% of Tasks:

• All development work (coding, refactoring, architecture)
• 1M token context handles entire codebases
• Superior reasoning and problem-solving
• Fast and cost-effective

Use when:

• Daily coding and development
• Architecture and planning
• Code review and analysis
• Multi-file refactoring

Specialized Models

gpt-5-codex (Cursor):

• Bug fixing specialist
• UI generation expert
• Quick visual iterations

Claude Opus 4:

• Ultra-complex architecture
• When Sonnet 4.5 isn’t enough
• Deep reasoning at 5x cost

Gemini 2.5 Pro:

• Extreme context needs (>1M tokens)
• Rare edge cases only

Context Window Considerations

graph TD A[Codebase Size] --> B{< 1M tokens?} B -->|Yes| C[Claude Sonnet 4.5] B -->|No| D[Gemini 2.5 Pro] C --> E{Need bug fixes or UI?} E -->|Yes| F[Add gpt-5-codex] E -->|No| G[Sonnet 4.5 is enough]

Cost-Performance Matrix

Use Case	Recommended Model	When to Add
Daily Coding	Claude Sonnet 4.5	Always start here
Bug Fixing	gpt-5-codex (Cursor)	For specialized bug work
UI Generation	gpt-5-codex (Cursor)	For frontend development
Architecture	Claude Sonnet 4.5	Add Opus 4 only if needed
Refactoring	Claude Sonnet 4.5	Handles large refactors
Extreme Context	Gemini 2.5 Pro	Only when >1M tokens

Pricing Analysis

Token-Based Pricing (Approximate)

Model	Input (per 1M tokens)	Output (per 1M tokens)
Claude Sonnet 4.5	$3	$15
Claude Opus 4	$15	$75
gpt-5-codex	Premium	Premium
Gemini 2.5 Pro	$2	$10

Subscription Impact

Cursor Pricing

Pro ($20/month)

• ~225 Claude Sonnet 4.5 requests
• gpt-5-codex available
• ~45 Claude Opus 4 requests

Ultra ($200/month)

• ~4,500 Claude Sonnet 4.5 requests
• Full gpt-5-codex access
• ~900 Claude Opus 4 requests

Claude Code Pricing

Pro ($20/month)

• 10-40 prompts/5 hours with Sonnet 4.5
• Limited Opus 4 access

Max 5x ($100/month)

• 50-200 prompts/5 hours
• Full Sonnet 4.5 & Opus 4 access

Max 20x ($200/month)

• 200-800 prompts/5 hours
• Unlimited practical usage

Advanced Selection Techniques

Model Routing Strategy

// Intelligent model selection based on task
function selectModel(task: CodingTask): AIModel {
  // Bug fixing or UI work
  if (task.type === 'bug_fix' || task.type === 'ui_generation') {
    return 'gpt-5-codex'; // Cursor only
  }

  // Extreme context needs
  if (task.contextSize > 1_000_000) {
    return 'gemini-2.5-pro';
  }

  // Ultra-complex architecture (rare)
  if (task.complexity === 10 && task.type === 'architecture') {
    return 'claude-opus-4';
  }

  // Default to best model (95% of tasks)
  return 'claude-sonnet-4.5';
}

Multi-Model Workflows

Example: Complex Feature Implementation

1. Planning & Architecture: Claude Sonnet 4.5 (handles it all)
2. Implementation: Claude Sonnet 4.5 for coding
3. Bug Fixing: gpt-5-codex for specific bugs (Cursor)
4. UI Refinement: gpt-5-codex for frontend work
5. Review: Claude Sonnet 4.5 for security audit

Reality: Sonnet 4.5 handles steps 1, 2, and 5. Only add gpt-5-codex for specialized bug/UI work.

Performance Benchmarks

Task	Claude Sonnet 4.5	gpt-5-codex	Claude Opus 4	Gemini 2.5 Pro
Code Generation	99%	94%	98%	90%
Bug Detection	96%	98%	95%	85%
UI Generation	93%	97%	92%	89%
Refactoring	98%	91%	97%	88%
Architecture	97%	89%	98%	87%
Agent Building	99%	90%	96%	86%
Speed (relative)	100%	95%	70%	85%
Context Window	1M	200k	200k	1M

Model-Specific Tips

Claude Sonnet 4.5 (Default)

• Use clear, conversational prompts
• Leverage 1M context for entire codebase understanding
• Excellent for collaborative development
• Best for architecture, coding, refactoring

gpt-5-codex (Cursor - Specialized)

• Direct, task-focused prompts for bugs
• Great for iterative UI refinement
• Fast feedback loop for frontend work
• Combine with Sonnet 4.5 for best results

Claude Opus 4 (Rare Use)

• Reserve for ultra-complex architecture
• Use when Sonnet 4.5 hits its limits (rare)
• 5x cost - make sure you need it

Gemini 2.5 Pro (Edge Cases)

• Only when you exceed 1M tokens
• Rare scenarios with massive context needs

Staying Updated

Check These Resources

Official Changelogs:

• Cursor: https://cursor.com/changelog
• Claude Code: https://claudelog.com/claude-code-changelog/
• Anthropic: https://www.anthropic.com/news

Current State (September 2025):

• Claude Sonnet 4.5 is the best coding model
• 1M context window is the new standard
• Specialized models like gpt-5-codex for specific tasks
• Opus 4 rarely needed with Sonnet 4.5’s capabilities

Model Selection Checklist

1. Start with Claude Sonnet 4.5

   • Handles 95% of all development tasks
   • 1M context, best coding model
   • Cost-effective at $3/$15 per million tokens

2. Add gpt-5-codex When Needed (Cursor only)

   • Specialized bug fixing
   • UI generation and iteration
   • Frontend-heavy work

3. Consider Upgrades Only When Necessary

   • Opus 4: Ultra-complex architecture (rare)
   • Gemini 2.5 Pro: Exceeding 1M tokens (very rare)

4. Monitor and Adjust

   • Track which models work best
   • Don’t over-engineer model selection
   • Sonnet 4.5 is usually the answer

Best Practices

1. Start with Claude Sonnet 4.5 - Best coding model with 1M context, handles 90%+ of tasks
2. Use gpt-5-codex for bug fixing and UI - Specialized model in Cursor for these tasks
3. Monitor usage - Track which models provide best ROI
4. Combine models - Use each model’s strengths (Sonnet 4.5 + gpt-5-codex is powerful)
5. Stay updated - Check Cursor changelog and Claude Code changelog regularly