I'm gonna go with Rebel.
Reason #1: RPG 7
Reason #2: Uzi
Reason #3: Makarov
Reason #4: FLAMETHROWER!! (LPO something-or-other)
Reason #5: MGL-140
Reason #6: Cool goggles and mask.

I like every gun in the class.
The RPG is a blast to use.

The Uzi is the best side arm in the game.
I love Pistols and the Makarov is my favorite in this game. (It would be the Star .45 if only it fired as fast as it did in the single player.)
You really can't argue with a flamethrower... I don't use it often for fear of being banned. People tend to think the LPO as cheap and annoying. I know at least one person who shares my views on what is "Cheap and annoying" in this game.

The MGL-140 is a beast and the longest range gun in the entire game. Unfortunately, it doesn't own quite as much as it did without hardcore mode. Still, once you learn how it handles, you can put the shot anywhere you can see.
A bonus is that this is one of the classes that has grenades instead of Molotovs. We all know how useful molotovs are...
My favorite guns outside of this class are the Homeland 37, the FAL, and the M1903.
If the Guerrilla class had the Uzi instead of the Mac 10 I'd probably never use anything else.