You may try SeaMonkey too:

My vote is for Firefox.

Mozilla Firefox 2 & safari

Before Firefox 3, Safari and Konqueror were my favorite. They had a smaller memory footprint and were a lot faster in rendering.
With Firefox 3, that changed and now I used Fx3 as my primary browser. Still I believe the future is WebKit and not Gecko, that's why every time I'm behind a Windows box I use Chrome.
The things that matter to me in a browser are rendering speed and standard compliance.
Opera is pretty good on the standard compliance part, but when it comes to rendering I find it slower than other browsers. Maybe not rendering, but overall I find Opera a bit sluggish.

If only Microsoft will IE to more standard compliance, IE8 is a step forward but still not there yet.

For what it's worth, Firefox embraces and extends the use of the location bar as a general input to search engines etc. The little Google box next to the location box is basically redundant. In FF3 they call it the "awesome bar"; whoever came up with that term should be forced to work in marketing.

Firefox 3, because of 'tabbed browsing' and hassle free plugins, such as 'Speed Dial' and Gmail Manager.

Firefox - It still has some memory problems but its the best for security IMO.

The evolution of the experience...

I cut my teeth with lynx back in '92. I clearly remember stumbling across ncsa mosaic (and hating trumpet winsock) in late '93. In 1994 I must have tried a good (bad) dozen "next great thing" browsers before settling on Netscape.

Firefox is my poison these days. It behaves pretty consistently across systems, and aside from a handful of Windows specific client application requirements, serves me fine.