Opera is one of those pig headed apps that doesn't use Cocoa, it's okay on Windows or Linux.
FireFox has problems too, but on Windows or Linux it's the best, worth the speed penalty because of its plugin system.
I would use Camino if it had extensions, but right now it isn't worth the speed penalty.
Safari isn't feature rich, but it's the only browser that isn't a kludge on OSX, aside from Camino, but it's slower.
