There are 3 categories of browsers for Android from my observation:
1. AOSP-based: These browsers can be further categorized into two sub groups
a) Stripped AOSP: These browsers aim for speed over functions/features, and you can usually tell them by their names (Lightning, Fast, Naked, etc,.)
b) Copy of AOSP: Typical webkit-based browsers that mimick AOSP but with twists and tweaks. Some may offer unique features that are not found in AOSP browser with log-ins (Dolphin, UC, Maxthon, etc,.)
2. Full-fledged desktop counterpart: While they are nowhere near versatile as the real desktop browsers, but they strive to be one. Offers rich experience with add-ons and plug-ins. (Firefox, Opera, Chrome)
3. VPN-based: These are what they often call 'mini' browsers. Through server-side rendering they often reduce the data traffic to users dramatically. Best suited for very slow network or very slow hardware, for text-based pages. Notably these browsers will not work with sites require higher level of security for obvious reasons.
I use at least one in each category. I use AOSP for speed, Chrome for sync w/ desktop. But majority of my browsing takes place on Firefox and opera. Familiarity and large open-source add-on community is the major reason to use Firefox. There are lots of add-ons that can be found, and I get to choose which one I will use instead of it being bundled with the browsers. Note its performance isn't great. Just like on desktop, Firefox can feel bloated and sluggish on slower hardware and is recommended on a faster hardware (S4 Pro or higher, Tegra 3 doesn't seem to cut it) Oh, and I kind of like its use of Open Sans.
In other times, I use Opera and its off-road mode. It is not fast at first visit to a page, but from there on it gets faster and very resource-light. It is my favorite for sites with lots of text. (e.g. forums)
I have dabbled with many Webkit-based browsers, and found them attractive at times, but eventually come back to the above. Those 'light' browsers are not adequate for rendering even text-based tables (misaligned tables, incorrect text-wrap, etc.). Other Webkit browsers try to distinguish themselves with little tricks here and there, but I would find something missing anyway. Some falls victim to 'Nero Syndrome' and try to be one-stop portal which I do not welcome, some are buggy, some lack features that I like (but nowhere can I find add-ons).