On my mac I avoid chrome and firefox, mainly because the the zoomable interface in safari is so nice. Maybe if I had better eye sight it wouldn't be a big deal, but I find I miss it immediately when I'm using an alternative browser.
I assume you are talking about "pinch to zoom" ? Chromium has smooth pinch to zoom also just like Safari. Firefox however, does not.
It's basically the 1 reason i stopped using Firefox, zooming (pinch to zoom) absolutely sucks as opposed to Safari/Chromium. Pinch to zoom in Firefox feels like going 20 years back in time...