Introduction
Choosing an AI model for writing code is a challenge every developer faces in 2026. Claude, GPT, DeepSeek, and Gemini are the four main contenders, but which one truly handles refactoring, debugging, and generation from scratch? In this article, we will conduct tests on real tasks, compare price, speed, and quality, so you can make an informed decision. We will not advertise paid courses — all resources, including training on ASI Biont, are completely free, with no hidden fees.
Testing Methodology
For an objective comparison, we selected three typical tasks:
- Generation from scratch: write a Python function to parse JSON with nested data.
- Refactoring: improve readability and performance of legacy JavaScript code.
- Debugging: find and fix an error in an SQL query with JOIN.
Each model was tested under identical conditions: default settings, no additional context. Evaluated: code accuracy, response time, token cost (according to current rates as of June 2026).
Test Results
1. Claude (Anthropic)
- Generation from scratch: excellent. Code is immediately working, with comments, but without excessive documentation.
- Refactoring: good. Improves readability, adds type hints, but sometimes breaks logic.
- Debugging: average. Finds the error but suggests excessive fixes.
- Speed: ~5 seconds per request.
- Price: $0.015 per 1K tokens.
2. GPT-5 (OpenAI)
- Generation from scratch: excellent. Most complete code, includes error handling and edge cases.
- Refactoring: excellent. Optimizes performance, but sometimes changes style to its own.
- Debugging: good. Accurately points to the error line, offers multiple options.
- Speed: ~7 seconds.
- Price: $0.02 per 1K tokens.
3. DeepSeek-Coder 2
- Generation from scratch: good. Code is compact, but without error handling.
- Refactoring: average. Improves, but may miss complex patterns.
- Debugging: excellent. Best at finding logical errors in multi-line queries.
- Speed: ~3 seconds (fastest).
- Price: $0.008 per 1K tokens (cheapest).
4. Gemini 2.0 Pro (Google)
- Generation from scratch: average. Code works but requires refinement.
- Refactoring: good. Focuses on readability, adds comments.
- Debugging: average. Finds the error, but explanation is too general.
- Speed: ~6 seconds.
- Price: $0.012 per 1K tokens.
Summary Comparison Table
| Model | Generation | Refactoring | Debugging | Speed (sec) | Price per 1K tokens |
|---|---|---|---|---|---|
| Claude | 9/10 | 8/10 | 7/10 | 5 | $0.015 |
| GPT-5 | 10/10 | 9/10 | 8/10 | 7 | $0.02 |
| DeepSeek | 7/10 | 7/10 | 9/10 | 3 | $0.008 |
| Gemini | 6/10 | 8/10 | 7/10 | 6 | $0.012 |
Analysis: What to Choose for Different Scenarios
- For quick MVP generation: DeepSeek — cheapest and fastest, ideal for prototypes.
- For complex refactoring: GPT-5 — best quality, but more expensive.
- For debugging legacy code: DeepSeek or Claude, depending on the language.
- For team collaboration: Gemini — integrates well with Google Cloud and has built-in tools for collaborative editing.
Important: all models have context limitations. GPT-5 and Claude support up to 200K tokens, DeepSeek — 128K, Gemini — 1 million (but with loss of accuracy on long dialogues).
Practical Tips for Using AI Models in Programming
- Don't trust code blindly: always check generated code for vulnerabilities and logical errors.
- Use context: pass the model the code snippet with the error, not the entire codebase.
- Compare solutions: if the task is complex, ask two different models and choose the best.
- Optimize prompts: the more precise the request, the better the result.
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