Is cacoon the best "oh shoot" button for healers?

As i start my healer journey this season I have played a little Rdruid and starting to play priest once i do enough BGs.

I realized that i am slow with reaction time and spend more time looking at healthbars (i dont know if that is good or bad) - but witht his burst i would really like a reliable boom heal.

What healer provides that? thanks!