I prefer Seamonkey, but sometimes I use Firefox, too. However, since some recent version, there are two things that I do not like — no easy way to put the tabs below the toolbar, as they used to be, and getting rid of the new tab page (completely). Some searching pointed me to the solutions.
For the tabs, open
about:config, and change the value of
false. Restart the browser.
To fix the new tab page, go to
about:config again, find
browser.newtab.url and change its value to
about:blank. For the record, I do not have privacy / paranoia issues, it just annoys me.