I started leveling a sorc, and she is still lower level, but I'm pretty sure it must be the most op class for soloing harder mobs and quests. Bubble, heals, damage, and cc, and a pet to tank for you. CC is the most powerful thing, next to being able to heal.
When I was leveling my marauder, I was able to do all my heroic 2, heroic 4 with droids, and a few without droids. I don't know if it's possible if you're not annihilation spec for marauder, because the heals from dot crits seem practically required, especially while killing the first one or two mobs of each pack. Also I'm biochem, so having the reusable self/companion heal medpac made a big difference since sometimes I needed to keep 1 mob on Quinn, or it was too much damage on me. Using it will res your companion if they are dead too. Hardest packs were those 5 gold, 3 gold/2 silver, 4 gold, and then anything less wasn't too bad. The interrupt/obfuscate talent helped a lot too, especially for champ mobs.
No video but I have a couple random screenshot. http://imgur.com/a/KHtd7