My favorite: Miren
After reading this thread, I tried almost every browser available to see which I liked. Surprisingly, my favorite (and now default) browser is the Miren Browser. It is quick and has a clean interface. The tabs are great. The current tab only has a big X, so it's easy to close, but the inactive tabs show text. There are "floating" back/forward buttons at the bottom or you can swipe from the edge of the screen to go forward or backward instantly. It uses the global bookmarks for your phone and has a handy start screen with a "Speed-dial like" bookmarks portion. The other great thing is you can personalize most of it's functionality, so if you don't like the swiping or the floating buttons you can turn them off.
The biggest problem I had with the built-in browser was it's awful tab management. It took far to many presses to do anything tab related. I use Opera frequently on my computers, but the Android version (still in beta) is lacking. It doesn't handle Flash well, but does have a clean interface. I'll probably check back in with it once it's out of beta.
Dolphin HD was probably my second favorite. It is highly customizable and supports add-ons, which is nice, but mostly unnecessary. My biggest qualm with it was the cheezy interface. The tabs are tacky and look like a button off a 1990's web site. Sure you can change skins (I prefer the blue one), but all they do is recolor the tackiness. The little x's on the tabs were also difficult to hit at times. And I find the gestures to be annoying. I'd prefer a back and forward button.
xScope is almost a tie for second, but the I think I just preferred the tabs in Miren. xScope is certainly worth a try though.
Skyfire might be nice for those that are really into social networking, since it has a toolbar devoted to it. Otherwise, once you get past the fancy intro video thing, it's pretty disappointing.
My biggest recommendation is to try them yourself and pick your favorite. Hopefully this post will save you a bit of time in your quest.
