Marco Arment recently wrote about why he keeps using Firefox:
… I’ve become addicted to its URL substring matching for autocomplete: for example, to go to the Tumblr Dashboard, I just type “dash” (autocompletes to
http://
w
ww.tumblr.com/dashboard
based on the substring match), down, Enter. In Safari, I’d have to type “tumblr.com/d” at minimum, and I’ve never quite been able to reliably use Safari’s autocomplete without frequent accidents.
I find myself messing up with autocomplete in Safari a lot, but I always keep two browsers open. I surf, search, bookmark and preview in Safari, but I troubleshoot in Firefox with Firebug. Safari’s Web Inspector is nowhere near what Firebug is. I think WebKit guys should just straight copy it.