Dolphin HD user here. I think it's far superior to the stock. All the stock does is browse....big whoop. In this day and age...come with more. Dolphin does this. Also...the Bookmarks widget for the stock browser doesn't let you customize your widget to display your favorite bookmarks accordingly....FAIL.
On the other hand...you download "Bookmarks to SD"....use the widget and you have 6 bookmark favorites in the widget and a window of those sites displayed in said widget. The widget uses the top 6 bookmarks in your Bookmarks folder of Dolphin HD browser. Move for instance "Ebay" to the very top....that will then reflect on the Bookmarks to SD widget. Click on a little window bookmark of a site....like "Android Evo 4G forum" and it takes you directly there. Piece of cake.
View the widget here on bottom left corner:
THANK YOU!!!! (for pointing me to this widget). Although I would like to point out that the widget does not come with "bookmarks to sd" and is a seperate dolphin bookmark widget (
Bookmarks Widget - Android app on AppBrain thats the same one metioned here right?)
Anyways, I was just using stock browser for a while and funny enough the thing that drove me to Dolphin HD was that in stock, if you click on a youtube link it just takes u to the page and plays the youtube embedded on the page. In dolphin, you can choose to open with youtube player. This is NICE because the youtube player on our beasts of a phone is GOOD quality.
That being said, main things I think are better is that Dolphin HD is faster, and you can turn on "fullscreen" which just takes all the clutter off the screen (which Dolphin HD has WAY too much of IMO, stock browser is nice and clean; this WAS a +1 for stock, but using fullscreen mode in Dolphin is even better

).
EDIT: With fullscreen on, and in landscape, if you have decent eyes you can actually read the content on the page (Check out NY Times like this) which is awesome
The main drawback I had was that I liked the bookmarks plugin for stock browser and it was hard to get the 2 to work together (you could kinda get the 2 to work together by making dolphin the default, but it still wudnt let u add pages and stuff). But now I actually like this widget better because its a little smaller (wtf is with HTC and these mamoth sized full page widgets? lol).
Last but not least, I do have Skyfire installed ONLY for pages that have streaming videos on them (that are not youtube vids). Skyfire is extremely nice with those and loads the video in an awesome quality (as far as streaming over 3g goes) android-friendly format. I do heavily recommend that. Dolphin HD seems to do embedded videos too, but it doesnt hurt too much to have a different browser to use for that stuff if you know you are going to do it.
To sum up, my browser usage:
Dolphin HD (90%)
Skyfire (10%)