Finally got around to reading all the Girls Und Panzer stuff, and I've gotta say this is the best of the three official series. Motto Love Love got a bit too nuts at times (although canon Orange Pekoe x Darjeeling was nice) and the original series was kind of disappointing. It simply didn't deliver on the tension or a lot of the interpersonal relationships.
On the other hand, Little Army was really satisfying in a lot of the ways the original series wasn't. You got a good feel for the characters both as kids and as a team, and their issues really seemed to mean something.