theres just some things that dont work IMO on all 4 'native' browsers (IE,OmniWeb, iCab, Mozilla) all have their individual deficencies.
IE is lacking its XML support and well is still pretty buggy. compared to IE 5 for macos9, it needs polishing. and even that older version was somewhat buggy. the carbon version has lots of serious bugs. repainting issues galore.
OmniWeb has some serious javascript incompatibilities with the stuff i need. main site is our company's Outlook Web Access which is HEAVY on the javascript. otherwise OmniWeb looks great, is slimmer than IE (which isnt hard... sometimes i think Microsoft shoulda been called MemorySoft...)
iCab works great all round. but has some lacking in the java support. aka, needs some. which they know, and are working on. its nice and small, and quick.
Mozilla... well... its definatly still a work in progress for the mac port. lots of weird things that dont work. like dropdown menus. they appear somehwere else on the screen, and dont always work right. and it actually uses more memory than IE. which is what i expected since all the Mozilla distributions are pretty big memory users.
all in all, my main browser is still IE. i hate to say it, cuz i am not a fan of microsoft, but under os9, i was blown away by the little things in ie5. plus the xml support is helpful for my work. but under osx, even with out that, and the little times i need to kill it off, i think its the best one overall.
if i need to do stuff like check my work email, i'll fire up iCab. sometimes i'll use OmniWeb, and even less rarely Mozilla.
i just wish Mozilla were a bit more polished...