I'd think shaman would be your best bet for group healing while still remaining a bit durable. Druids can take quite a bit if they ate spinning 3 lifeblooms and rejuv and regroth on them selves but that takes a bit more hands on than most boxers want. Shaman can chain heal in these situations they wear mail and have a shield and if they die you get another try without argo in the form on ahnk. Palls are great single target healers but group damage is not their thing. A resto druid in bear form is still weak and now they can't heal. Feral druid gear has alot more armor than resto gear so where a feral druid would have 25k + a resto in bear form would have 10k and no defense so you would be crit to death fast with no incoming heals.

Resto druids would be better than pally's as multi target healers but not as good as shaman or priests.