My personal favorite is Maxthon, but Maxthon 2 is still in RC stage so I'm just using Firefox for now.
Firefox is pretty good. Lots of plugins, addons and themes, but it's not really that lightweight browser it once was back in 1.0. Now there's actually quite a bit of code bloat. Still works well for what it is, despite the fact that Internet Explorer still trumps it with Flash and Java heavy sites. Read this:
Internet Explorer 7 is a bit different than 6 so it might take getting used to the different UI, but it's definately a step up from before. The only disadvantage is that updates are from the Windows Update, so it takes time to keep up to date. Other than that, it's probably one of the best performing browsers around. Sites load very fast and no matter what fanboys say about it, it's still a very good and capable internet browser.
Opera is good. Unfortunately, it's strength is also it's weakness. It has a lot of features which in turn complicates the interface. When I first tried it, I was overwhelmed with all these features and the unorthodox layout of everything. Eventually I gave up on it because it just made browsing the internet more of a hassle, rather than enjoyment.
Safari...well...it just, for the lack of a better word....sucks. Even when using my sister's Powerbook Titanium G4 notebook I use Firefox or Camino. I see no performance difference despite Apple's claims otherwise. The user community isn't as abundant as Firefox's or other open source browsers. Safari for Windows is just a plain mess and in a nutshell is a very, very poor port of a browser. A lot of the things originally designed for the Mac OS X interface are still retained even though Windows does it differently. One of the more forgettable Apple offerings. No thank you.
I never tried Seamonkey, so I can't really comment on that. Camino is basically Firefox but specifically designed for the OS X. It uses the same Gecko engine as Firefox and pretty much all the features from Firefox are the same.
Maxthon is definately a browser everyone should try at least once. It's very lightweight and simple. It uses the same engine as Internet Explorer but combines the features of Firefox without all the code bloat. So as a result, your browsing experience will be fast and at the same time, easy to use with plentiful features. Yay!
Of course, none of what I've said really means anything unless you've tried it. The most important thing is that you give all the browsers a whirl and see which one suits you. Everyone will have different preferences so don't just count on word of mouth.