Best AI tools to use for studying faster, suggest pls?

I know some basic AI tools like Chatgpt, Gemini, copilot, Claude. I need something like a study assistant tool which can help me research and learn concepts faster and better in accuracy. Most of the research lies around computer science, programming, learning theory behind a logic, lifestyle, design, itineraries, philosophy, life coach etc Suggest me some that can be useful free and paid both (is the paid version worth it ?)