A great topic!
The Legions of Steel UNE line of minis is probably my top pick. The UNE heavy assault troopers are my personal favorite, not fancy at all but they give me a real feeling of solid, heavy powered armor soldiers. Honorable mention goes to the big UNE walker; the B52 bomber body shape was kind of a dorky idea, but the end result actually looked impressive.
The GW tyranid line is my guilty pleasure pick. Yeah, they are big gaudy over-blown figures from GW, but that's OK because they are monsters.

The creatures are sinister looking, and (as Sylvas mentioned below about the Mordhiem figures) the plastic sets allow a huge varaty of poses among the grunts, even before "bashing".
Closer to home, Mishima is my favorite Warzone army, but then I have always had an interest in samurai. I definitely like the Mishima Bushido Samurai. The Hatamoto are merely OK, hampered by those overly gaudy scupts, but for some reason I really love the Hatamoto Leader. I also like the look of the Ashigaru troops, probably because they are a step back to a less-gaudy, better-proportioned style of figure, which I am very partial to.