Guardian. It plays to both your wish for a saber and a tank. Has great PvE and PvP specs.
Military Stance? (Wierd Question, but IK it's a pretty big thing for trooper)
Definately a Trooper Vanguard here. Tank, great DPS, good pvp and pve specs and while it's a blaster class, it has loads of great graphical effects besides blaster bolts.
That being said, I personally prefer a Bounty Hunter because of the great companions and you get to burn everything to a smoldering pile of ashes
Paper beats Rock.
Rock Beats Scissors.
Scissors beats Paper.
Fire and brimstone beats ALL OF THE ABOVE.
And to make sure nothing survives, you can spam missiles while flying with your jetpack.
Vanguard for a good military story. And if you like Mass Effect make it a female character (FemShep voice actor).
Guardian for your typical heroic saviour of the galaxy story (the usual Star Wars archetype story).
Powertech BH for a personal story with a good group of companions. The overall story lacks a bit, but is more than made up for because your companions are relatable.
Vanguard/Powertech and Guardian both excel in either field.
It would be AWESOME if you could rank the classes I might enjoy the most (1-8 obviously) because I haven't played them all and don't have the time to.
1). Vanguard or Powertech (depends on if you prefer a military story or amazing fiery skills of doom with fun companions)
2). Guardian (Saber. Hero. Great PvE. Great PvP. 'nuff said)
3). Consular Shadow (Saber. Plague thing appeals to you. Stealth is awesome.)
4). The rest.