It seriously just comes down to faceroll. Sages/Sorcs are the quintessential faceroll healer. There is absolutely nothing complicated about how to heal except for remembering to use your Noble Sacrifice after every Healing Trance. And even if you forget, you still have the energy resources to be ok. They also do great damage for being healers since their DPS and Heal Sets are itemized the same (no need for Accuracy like the other two).
Scoundrels/Ops are definitely the FotM, though I have used one since launch. Their infinite energy and mobility if played right are definite perks that make them incredibly strong. They don't pack the "oomph" in strong up-front heals to take care of 2 or more players at once, nor do they handle AoE healing as well, but they are definitely good healers. It took me a little practice to be as good as I am with my Scoundrel, but I was able to Heal out the box on my Sage in Hard Mode KP without a single hiccup (that's how easy they are).
All of the healers have their niche. Commandos have strong single target protection, Scoundrels have their mobility and infinite energy, Sages have their AoE and do well healing multiple targets. All 3 can tank heal like champs. All 3 have no energy problems if managed correctly (Commandos need more knowledge of fights so they know when is heavy healing and when is energy regening phases).
When I play my Sage healer, I have no issues chain-pulling in Flashpoints, in fact I am usually the one pushing for us to do so. Sages have near infinite Energy as well if played right. And I have seen Sages and Commandos solo heal Story Mode Ops as well... even Karagga's Palace. It generally requires DPS who can heal to help out on occasion, like during Fabricator Droid, but it is entirely doable for any healer who is good and geared.
i have never been out healed by any healer(same gear) with my scoundral. I can crit heal over 7k we chain pull. the secret to scoundral is main stat. more main stat allows more crit chance. I never not crit on my heals. we farm sm ev/kp for our noobs gear and i solo heal them. and im only geared in columin gear with a couple bh/rakata jewlery. ive been in pug hmfp with people in orange lvl 50 stuff and power healed through it. i had a tank who had lvl 41 stuff lol and we did it nonstop pulling. I'm sry but no one can convince me anything is better than a scoundral healer so far. you want aoe heal? i can double hot everyone faster than a sage can aoe and people run to the puddle.