I like the second one mostly. I don't like the "floating text" deal with the third one, but I'm sure quite a few people like to have their actual Hit Points visible [I for one don't care, I only stare at a small bar that has Player, Target, and Implied (Profit's)].
Just thinking ahead, will you offer the group in horizontal format? I like to have mine as compact as possible (height wize) across the bottom, just above my chat and hotbars of Letterbox.
Also, not sure what you have planned for "fill", but when you do it, if you can, maybe put some kind of outline or bevel on it to make the complete guage stick out. It's easier to view the battle that way IMHO.
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