Chimera is beta, wait for 1.0 release.
Actually, it's in the alpha stages still, but it's rendering engine has been in use for years and is very solid, stable and fast. Chimera is my default browser now due to it's speed, stability and support of standards. I like to live on the bleeding edge, so it's incomplete feature set doesn't bother me. I'm a basic browser user anyway, skipping out on all those extras that IE offers (scapbook, etc). Plus, tabbed browsing rocks.
Netscape 6/7 is slow, don't use it.
Depends on your reference machine. Mozilla/Netscape does have the slowest application performance, but again, due to the Gecko rendering engine, seems to render pages quite fast on both my machines (see below).
OmniWeb is a piece of *****.
Ouch! Quite harsh. I disagree completely. OW has a great front end, and renders pages faster than IE (but still slower than Chimera). It has lots of features, like subscriptions, sidebar, and lots of other little nice touches. However, it's the least stable of the batch, and it's rendering engine has a long way to go before it comes near the standards support of both IE and Gecko.
Microsoft Internet Explorer is fine. Yes ! It is ! Try it !
It's pretty well rounded. But for my use, it is way too slow. The next IE update and OS X 10.1.5 will give it antialiased text, which is a nice boost, but it needs major optimization under OS X. Currently, it's just way too slow for me to even consider using.
As for Opera and iCab - Opera makes you look at ads if you don't pay their fee - which is ridiculous. iCab has some nice features, mostly it's small footprint - but again, it's lame support for standards, especially in java/javascript and CSS remove it as an option for me.