First Place: Master Strategist
I have something of a soft spot for simple but diverse martial PrCs, and this is a really simple, really diverse martial PrC. Great use of the theme, and there's a strong underlying concept of the general, leading his men from the front lines. The fact that the class is geared specifically towards mass combat was quite interesting, too.
Second Place: Taxiarch
Another strong concept here, almost feeling like the evil psionic counterpart to the master strategist. The use of the stratagems feels a bit clunkier here, I must admit, but it ties together well. I particularly like some of the non-combat powers, too- particularly Empathy and Sensory Network, they feel a lot like powers that a scheming psychic strategist would use. I have no idea what's going on with power points per day, though. Maybe there's some logic that I'm missing, maybe it's a typo, whatever.
Third Place: Guileful Striker
While it lacks the diversity of the Taxiarch or the Master Strategist, I like how the Guileful Striker manages to use the theme without overwhelming itself with options and text- in short, it manages to deliver on the theme with useful abilities without spreading itself too thin and remaining easy to use, something that some CORE PrCs don't do well.
Most Likely To See Play: Guileful Striker
The simplicity of the Guileful Striker is largely what leads me to put my vote here. A simple class is easier to play than a more complex one, by definition, and a Guileful Striker opens up options that are useful to have on an intelligent fighter-type character, and fit the role well.
Most Unique Entry: Taxiarch
Conversely, complexity tends to make for unique entries, and the Taxiarch is no exception. I liked the way that martial and psionic combat was combined in this entry, and the powers granted by the strategems were well thought out and fit the theme well. Close runner up here is the Master Strategist for much the same reasons, minus the combination of combative techniques.