...heard Pournelle mentioned and would definitely recommend Falkenberg's Legion. Bujold and Weber are mainstays, and Bujold's works go beyond the military genre. I also enjoyed Moon and Ringo, and the various collaborations those two did with others, especially the Weber/Ringo series. While not really military SF, I'd also recommend James Alan Gardner's Expendable and subsequent titles. Ender's Game is one of my desert island books (along with the Stand and, of course, Tolkien's collected works) and I thought Ender's Shadow was also quite good, but never really enjoyed Speaker..., Xenocide, etc.