Lately, I've been using Omniweb a lot. I liked it well enough to yak up the $14.95 license fee, after trying it out.
Fast? yep, it is. Totally OS X native. Best feature: The abiltiy to set preferences for each site you visit. The ad blocking is wonderful. It doesn't have that "Cross platform" feel of Firefox. Firefox is a great browser, but I prefer a totally OS X native app whenever possible.
Not perfect though. Some scripts do seem to have issues. I have been using it for four months, and it has crashed twice. Not bad at all, but Safari has never crashed at all.
The Tabs feature on Omniweb takes a little getting used to. The Google search bar cannot be resized on demand, as it can with Safari.
So, not perfect, but still a great browser. I'd suggest using the trial version, and see what you think. Nothing ventured, nothing lost.