Many industry reports are saying that Google's Chrome browser is moving ahead of Mozilla's Firefox. Yahoo ran a story yesterday about this. This trend can be seen in this blog. When looking at the numbers over the past 30 days, Chrome just edges Firefox in terms of pageviews.
I prefer Chrome since it is fast and simple. It lacks many of the gadgets and add-ons of Firefox but requires less maintenance than Firefox. This article below in Search Engine Watch gives a good account of how Chrome moved ahead -- which seems as much a result of bad moves by Mozilla as good strategy by Google.