I use Chrome or Firefox built in developer tools, however I still think Firebug fits my workflow the best. Unfortunately it's too slow to use. The thing I miss the most is the inline display of AJAX call responses, and being able to write/run multi-line snippets of JavaScript (without ctrl+enter). Somewhat interestingly, Firefox built their entire add-on architecture because Joe Hewitt wanted dev tools (for debugging…
If I understood correctly, you can have this on Chrome. In Chrome JS Console, do a right click in an empty space, and select "Log XMLHTTPRequests" (or it was something similar).