📚 A practical guide to choosing AI research tools by freshness, citation traceability, document grounding, synthesis quality, privacy, and cost—not by one universal winner.
AI research tools differ chiefly in how they retrieve current information, constrain answers to supplied documents, expose citations, and support verification. Perplexity is strongest for fast web research, NotebookLM for source-grounded document analysis, and ChatGPT, Claude, and Gemini for broader synthesis when their search or research modes are enabled. No tool eliminates the need to inspect sources, because independent studies continue to find citation errors, incomplete attribution, and uneven source selection.