Commando is by far the weakest class when it comes to both damage and healing.
This is so far from being true this has to be a troll post.
I've leveled at least 1 of each republic class to 50 so my summary would be like this...
Smuggler - best story, survivability varies by spec, scoundrel has decent survivability due to access to heals, stealth and CC, Gunslinger less so due to lack of a humanoid CC, no heals and no healing companion until late game
Jedi Knight - 2nd best story, mediocre survivability because of good DPS, but lack CC and healing companion til late
Jedi Consular - 3rd best story, good survivability because of early healing companion and tools like stealth, CC and heals depending on the spec you play
Trooper - Worst story (still good, just not as good as the others IMO), great survivability due to getting healing companion early, heavy armor and either CC or tanking abilities depending on spec
Story quality is totally my opinion, and I'm sure some would disagree with my rankings. All the stories are good, this was just my rankings of which one I liked the best.