I use DolphinHD. The stock browser is alright. Just a bit slow and not tabbed. You would have to manually exit out of each tab every time, whereas in DolphinHD, you can see the tab above the webpage and just hit the exit. The bookmarks are very clean. I have tried Opera-mini and didn't like it too much.
There is one other browser, that I have been waiting for a long time on, called Firefox. This browser seems to be still in the Beta stages after months and months and I don't even know what is taking them so long to get a perfect one out. At first it was a HUGE download (49mb), very bulky, very slow, crashed a lot, etc. But now they've reduced it to 13mb but still see a lot of complaints about it. Those Firefox team better get their acts together and get it out already because they are WAY behind competition. Everything they keep adding to it has already been done by another browser team. They blew away competition on the PC/Laptop, but cannot seem to do the same for the Android-based phones. Which is odd in my opinion.