K here's a real break down. The Dolphin HD is the most full featured web browser. It has all Flash features so you can watch embedded videos....plus it includes all site based features, main example being that you can go to the full facebook site and tag a friend in your status update. That is an example of it reading that the symbol (@) means to do something special, and it performs it (brings up the options for your friends when you type letters). One setting you must change for all full sites is the 'user agent' : change it to 'Desktop'
Now Dolphin isn't the fastest rendering browser. For that I would go with Opera Mobile. I tried it last night for a bit and wow it flies! Does not have Flash capabilities nor does it recognize the status tagging which was a deal breaker for me. Another knock I have is it does not have a 'desktop' user agent, so if you try to go to Facebook, espn, etc, it first loads the mobile site, and you have to tap on something to take you to the full site.
It also does not use the web address bar as a search engine, which I like on Dolphin as well (ie type in espn and it takes you to a google search of espn where you can then tap espn.com)
Stock is okay but just like when you get a PC, you start with a preloaded web browser that is pretty plain vanilla...not bad but nothing special
So maybe I sound like Aaron or Noah from Phone Dog (yes I know Noah is no longer with Phone Dog) saying "It depends what you want" but it really does....if you want speed, and are okay with compromising a couple features, go with Opera Mobile....if you want the most full web experience possible, and are okay with waiting an extra second or 3 (really not much longer than that)for the page to load, go with Dolphin HD.