Which one should I pick for a new project?

I can't advise you on which repository to pick without understanding your project's goals. These are two very different codebases:

thealgorithms/python is an educational resource—a collection of algorithm and data structure implementations for learning purposes. Per the README, "Implementations are for learning purposes only. They may be less efficient than the implementations in the Python standard library."

vnpy/vnpy is a production-grade quantitative trading system framework. It's a fully-featured platform with real dependencies (PySide6, pandas, ta-lib, etc.), targeting financial institutions and traders.

To help me give you better guidance, tell me:

• Are you building an educational project, or a production system?
• If trading-related, do you need a complete trading platform or just algorithm implementations?
• Do you need external dependencies, or prefer standalone code?

Once you clarify your use case, I can point you to relevant parts of either codebase.