Healing as a sorc is one of the more laid back healing specs in my opinion. With the other two healing specs you have to worry about resource management a lot more but healing sorcs benefit from a pretty easy to manage resouce pool and the smartest healing ability in the game.
I'd like to have some pics here but I don't quite know how to do that...so rip (KWAGAR TEACH ME). With 5.0 the previous 3 tiers of utilizes was bumped up to 4 (so you're not going crazy if you thought there were less).
Anyways, when it comes to PvE there are often "best" specs to use in general and for specific boss fights. For PvP it's a little different with specs not really coming down to the best or worst but more choice.
With that said there are definitally better specs than others. http://dulfy.net/2014/10/13/swtor-disciplines-calculator-swtor_miner/?link=dGEBAABGAgEAGgIGCQsPFQ0T is my personal favorite when it comes to 8v8s. Note the "personal" in the previous sentence as the following is all my opinion and could very well be corrected.
Tempest Mastery - Increase Force Storm damage by 25%. You're a healer and shouldn't devote too many GCDs to DPS abilities much less a drawn out channel of Force Storm. The only time I could see this being useful is when you're queued with 3+ other healers...in which case switch to DPS.
Dizzying Force - Whirlwind affects 2 peps nearby it's target and reduces the target's accuracy a bit. Again this is probably only useful in a few select situations with it most of the timing just being a waste.
Force Suffusion - Every ally within your Overload is healed by a small amount (up to 7 allies). Some people dislike this one given it only heals for a small amount, but in 8v8 I don't mind picking it. In 4v4s though I'd say ignore this one given 4v4s are more so a test of your burst heals and this one isn't bursty at all.
Dark Speed - Using Dark Heal increases the target's movement speed by quite a bit. I'd almost put this under a must have given that you use Dark Heal quite a bit for burst heals and this increases mobility by quite a bit.
Empty Body - Increases healing received by 5%. If you're having trouble staying alive or are getting focused a lot this could help you out a bit.
Sith Defiance - Increases your damage reduction by 3%. Any bit helps when it comes to damage reduction, especially in 8v8s when you'll be taking a lot over a drawn out time.
Torturous Tactics - Lower the CD of Electrocute and its target does reduced damage. While you should use electrocute every once and awhile there are better picks in this tier.
Corrupted Flesh - Reduces periodic damage taken. Could be Ok against DoT DPS but there are better picks in this tier.
Dark Resilience - Reduced damage taken by the target of your extrication (pull) and increases Unnatural Preservation's heal. The heal increase is 30% which I like a lot given my liberal use of U.P. and the damage reduction on the pull can be useful for players getting focused.
Supression - Cloud Mind (your threat drop) increases damage reduction (by 25%).
Lightning Barrier - Static Barrier does damage to attackers. While, yes, as a healer you should focus on healing but this one helps out with DPS quite a bit as you should have Static Barrier up on yourself most of the time.
Enfeebling Strike - Replaces your melee attack with a different melee attack with a root and slow. Despite maybe cool looking in RP duels, a force slow/force speed are probably just as good an option as using this ability when an enemy closes the distance...and they don't take up a Legendary Tier point.
Galvanizing Cleanse - Using your cleanse makes your next ability with an activation time activate instantly. This is pretty good to increase your burst heals and a useful way to remember to use your cleanse on targets, but I don't typically pick this one. I haven't ever really gotten used to using my cleanse a lot (aka Im too lazy) so with new players/not so advanced players (Kwaglet/Laggie) I'd say skip this one.
Unnatural Vigor - Reduces Unnatural Preservation's CD and it grants damage reduction upon use. I will often use Unnatural Preservation as a ways to heal myself without wasting GCDs for other low allies so if you're like me it can be a decent choice.
Force Mobility - I will ALWAYS use this one since it increases your mobility so much. In PvP as a healer you need to be able to kite DPS harassing you and being able to cast Innervate while kiting is a big help to your heals.