In the data-driven era of quantitative trading, the quality and stability of financial data directly determine the success or failure of strategies. In September 2025, yfinance collapsed entirely due to Yahoo's backend validation upgrade—all scripts without persistent cookies returned 401 errors. In October of the same year, Tushare Pro suddenly suspended operations, catching countless developers who relied on this interface off guard. By 2026, "unauthorized high-frequency scraping" was further clearly defined. The selection of financial data interfaces is evolving from "use whichever is cheapest" into an engineering decision that requires careful consideration. This article will provide a complete selection roadmap for individual quantitative researchers, startup teams, and enterprise-level users from two major dimensions—free and paid—combining four core indicators: latency, coverage, stability, and cost. I.…