I have used both the stock ICS and Gingerbread browsers as well as Chrome and Firefox. I think the best browser really depends on your device and your preferences. On my HTC Thunderbolt the stock browser crashed a ton and I lost all my tabs. Chrome wasn't out when I had that device but Firefox worked great and synced with my computer tabs (most of the time).
I use Chrome on my Droid Razr though, because it is better than the stock browser in my opinion, although the stock browser for the Razr on both Gingerbread and ICS is far superior to the stock on the Thunderbolt. Chrome is fast, syncs with my gmail bookmarks and syncs my tabs between my computer, my ipod touch and my phone. It also works reliably and quickly. I can open a page on my ipod or computer and see it on my phone in seconds. This works in all directions as well. So it is currently my favorite.