Keywords Everywhere is solid SEO extension. I love using it for keywords and estimated volume. The highlight feature is very helpful. And the best thing is the latest feature that suggest keywords on SERP, really amazing! That made me write this review. Hoping for more features or separate extension for metrics like TF CF etc. Best luck. - Sameer.
Have only just started using this, hence why I have given it 4* rating. So far I have found this tool to be extremely useful in my searches. The amount of data and analysis you get from it is simply amazing. Keep up the good work team! This tool - like the best things in life - is free!