Frankly I think too many people here are trying to say their is a "best" spell load out, I really don't think that's the case and I wouldn't want it to be. Different spell loadouts work best with different playstyles and i wish more classes in EQ were that way. However, a lot of stuff has changed recently, a big one being stuns providing decent healing with how much healing light has been boosted the last couple expansions. another being how much easier it is to cast spells with long durations like our group heal. I can easily get that spell off while tanking these days. with imperator's command it's really not that bad. a third being improvements to AA aggro, you can get by with very few aggro spells loaded these days, depending on how considerate everyone is with their ability usage, monks hitting their bp click after an add just spawned is bad form.
I agree that there's not really a "best" for pallies, because it really does change depending on a ton of different factors. Raid DPS to burn through mechanics / cause enough script lag that some things just don't happen, number of shammies for aoe heals, number of dedicated healers for off-tanks, how much of the stuff you're expected to off tank, how "good" your guild is at managing their own aggro, etc. Even event to event my loadout changes. I've got 4 different spell sets saved for various ToL raids. Now could I get away with using a generalist loadout for all of them? (with brilliant and splash in there) Yeah, probably but it would mean a sacrifice of other stuff so it's not worth it imo.
They're the best heals available you have that are versatile enough for you and others. Unlike splash which in a lot of situation is subpar (like if you're in a fight where you don't need the cure component and no extreme AEs). The problem of the stun you're using is it's sharing the timer with your best aggro spell to tag mobs and it seems more important in raid to rapidly get a mob on you rather than some unreliable healing proc of your spell cast. Burst and Valiant, you get to choose when you cast it, not healing light, it makes their healing way better.
Here is my tanking spell set: Crush 1/Stun 1 Crush 2/ Stun 2 Brilliant Hot Stun Composite Protective Valiant Quick Self Heal/Splash Honor Confluent Blessing/Audacity Stance Preservation Steel I've been playing with Stuns vs Crushes, but I haven't made a decision on which one I like more yet. I use Composite mostly as an emergency group heal than anything. I'll swap out Blessing for Audacity if I'm not getting single target heal. When I'm not tanking Brilliant 117 heal nuke 112 heal nuke Hymnal Flex Flex Flex Flex Flex Flex Flex Flex Flex LOL You can always tag with Parlay for Honor