Lately I have been using Chrome, but I am starting to think I should use FF. What are the advantages and disadvantages of the various mainstream browsers (with an emphasis on Chrome and FF) when doing web development?

Is it easier to start with clean code for a relatively conforming browser, and later add hacks/workarounds for acceptable display with less conforming browsers, or is it easier to work with a variety of browsers from the beginning, so we never have a page that's completely unacceptable with, for example, IE 6?