I'm using iCab, and it works fine most of the time despite being a beta.
The pages load nice, but sadly it is carbonized and not in all points conform to the display-standarts (like the nice prefs of omniweb).
It has many features I really like (like automatic update of a page whenever I save the html-document - I write the pages in textedit -).
It doesn't update the whole page if you use frames, but only all frames whenever you update the parent-page.
Sometimes it dies (espeacially the new version, I'm using one of the previous ones), but it can always be restarted instantly and only loses part of the history.
I already payed for it because I want to support the company, they have to pay more if I buy later and I already decided, that iCab will be my design-browser.
OmniWeb didn't display the pages as I wanted and was way too slow. so I stopped using it.
Internet(ex)bugger got really on my nerves, because it displays a start-dialog instead of launching silently as all other applications and it always jumped to the front whenever a page loaded successfully. The fact that it is from MS greatly supports my decision.
I will try the other ones instanty, thanks!
Computer: PPC G3 (oldest one possible
)266Mhz, 128MB Ram, 6GB; ibook 500Mhz 256MB Ram (can't use it due to the electromagnetic fields, which actually hurt each time I go near it).