Most mobile healer?

It seems and it isn't a bad thing that 5x tank are doing very well, while I haven't seen much for traditional tank/3 dps/healer. I do see 5x also somewhat being an option.

This expansion looks to have a lot of random damage, stuff to avoid - aoe all over so clumping as a group and navigating as well as being able to take or heal that damage is the number one priority.
With that in mind what healer is best suited to handle this if attempting a traditional setup. Last time I played I had Druid tank, 3 DK for dps and a resto shaman. This worked but the level of aoe and dodging seems to be much higher and unforgiving.

I'm sure I'll figure out the styles of each healer, but hoping to get some insight to put me on the right track.

Having not played in a while, I could be off.

It used to be that the Druid was the most mobile of healers.
A lot of their heals were instant cast heal-over-time.

That said, I personally found a Resto Shaman to be great in instances.
The Earthshield was a very strong mechanic, for the tank.
A benefit of going Shaman was the dual-spec option.

Earlier in an expansion, my 5-box PvE team consisted of:
Tank: Prot Paladin.
DPS 1: Demonology/Destruction Warlock
DPS 2/3: Elemental Shaman
Heal/DPS 4: Resto/Elemental Shaman

Earlier into an expansion, or switching to heroics after finishing the normal stuff...
It would be Prot Paladin, Resto Shaman, and 3x DPS on their click sequences.
The Shaman would have a mapped key to enter/leave the DPS Action Target Group.
So as a healer, my spam wouldn't do much aside from rebuff Water Shield and Earth Shield periodically.
Most of the controls were manual.
But I could respec the Shaman to Elemental (once that was introduced), and add them to the DPS ATG.

Later in the expansion, 3x DPS had enough healing with the Light/Fast heal.
And more DPS killed things faster.

The Earth Shield was essentially mobile healing, in that the tank was healed each time it was hit.
And dropping totems is on a single GCD, for all of them.
The healing stream totem did a fair bit of healing, with Resto spec.
The Paladin did have a few invulnerability abilities, for an emergency situation.
And the Shaman could self rez, for recovery if need be.

Agreed, it looks like the mechanics have changed slightly, wondering if that is sufficient. Guess only way is to try :)

Xeneres was using a holy paladin for heals and switched to a prot paly for heals. I would love to see someone achieve what Hes been able to ( Mythic+5.6? ) with a traditional team. I tried doing prot+holy+3rets and there is just too much damage going around. 5 prot paladins just feel good and get the job done, that's all i need really.

I'd like to know this too. Right now I'm just messing about leveling and seeing old content I've missed. Can't decide between shammy or priest. Once I get to the point I need to purchase legion x5 I can boost an all pally team to 100 if I need to. I'm just about ready to start on MOP stuff with Pally/shammy or Priest/3 hunters.

In MoP I was able to use a druid heal for PvP with great effect, you could spam for several minutes before going out of out of mana.
For PvE I was able to use Resto Shaman, Earthshield on the tank, and chain heal for the rest to make it easy. The problem after watching some of those videos is for a fight you may need to be moving 50+% of the time. That really hinders the ability to dps or to effectively heal while standing in something bad.

Which is why I would really enjoy the Enhancement shaman to be effective enough to heal with the healing rains, and do the instant healing surges as top offs.
If average character HP is 2 mil, and 4x healing rain is 100k per second total. That's about a 5% hp heal per second. I don't know if that is sufficient. They should only be taking AoE damage, but no idea if that's enough to overcome some encounters.

If I was to forgo any class synergy and didn't want to have the same armor type anymore I would of made my healer a druid instead of a paladin. They are without a doubt the most mobile healer in legion and also come with a battle rez.

The issue with hardcast healers like paladins is while they have very powerful, efficient and beefy single target heals, you still need to sit still and hard cast to make something happen. Sure, each healer has an instant cast or an ability they can cast while moving but druids can do that all the time. Druids may not have the best ability to top off spike damage quickly but they still have tools like swiftmend and they still have hard cast direct heals.

I gave each healer a try on the beta to see which would work best for boxing. I leaned on the paladin mainly because it had 20% mount speed (mirrors my DKs), plate, a tank spec and had bubbles and utility to cheese mechanics combined with my DKs AMS. Paladins healers by far have the most targeted ability utility in the game. I also wanted to try out prot and see if it was viable (which it is). Since holy paladins were redesigned to be a melee range healer they were given more hp than other healers so its a bit more tanky than other healers. I believe a holy pally even has more armor than a prot pally!

Disc priests seem like too much effort to maintain atonement. They feel like something with too high of a skill cap to multibox optimally. You would focus too much on them and not the rest of your toons. The damage they put out is lackluster.

Holy priest felt are kind of hybrid between resto druids and holy paladins. They feel like they have the most complete healing kit. This would be my 2nd pick after a resto druid for a healer for dungeons.

Resto shaman have very powerful Smart Heal and AoE CDs but cannot cast most of their spells while moving. I didn't like having to hard cast healing rain every 10 seconds

I didn't like mistweavers because they channel too much for their hots/healing and are quite mana intensive if you don't use your tea properly. Too much complexity imo for boxing.

After leveling my enhancement shaman team I did think about trying out 4x enhance and either prot pally or DK. I still think that despite how good rainfall looks on paper and how potent the heal is that they are still far too squishy with only one survival CD. Their AoE is also somewhat poor because it only hits targets in front of them. Positional requirements of abilities are typically not good for multiboxers. If your toons do the IWT "swarm" they may not be able to hit all of the mobs with crash lightnings AoE. The AoE pool from crash lightning and the talent is also quite small.

I ran my shamans through dungeons for their order hall questline on Normal of Eye of Aszhara and Neltharion's Lair. I ran 2-3 through at a time and I don't think that 4th shaman would make the difference in survival. The shamans were properly geared for the dungeon at 800-805 ilevel. I was still having to be very careful and move them out of AoE very quickly. In Eye of Aszhara my shamans died on Serpentrix when I had to kill the heads. They simply didn't have the HP and aren't quite tanky enough when they have to move out of healing rain.

I think this team would work but it would take more effort than a tank based comp. In Kara and higher difficulty dungeons melee dps no matter how geared they are get one shot by abilities if they mess them up or stand in them too long. Playing 5 tanks you get more breathing room to make mistakes and deal with the limitations of boxers.