In my opinion, the most valuable features in browser extensions are speed optimization, strong security controls, and ease of use without slowing down the browser. Features like ad blocking, tracker prevention, and phishing protection are important for a safer browsing experience, while tools that manage tabs, automate repetitive tasks, or improve search efficiency can greatly boost productivity. I also think good extensions should have a simple interface, minimal resource usage, and clear permission settings so users stay in control of their data. Overall, the best extensions are those that improve browsing without making the system feel heavy or complicated.