As a controller user, the setup I use for all healers is this:
All targetable DPS skills are macro'd with a <tt> (target of target) and at least one (usually the DoT) to also focus target the 'target of target'.
I lock-on/hard-target the tank.

Effectively this means I always have the tank targeted by default, I can see the enemy's HP, debuffs and cast bar, and when I need to target another player I can soft target them by hitting up/down on the d-pad, and as soon as I've used an ability on them, it instantly flicks back to the tank.
This is ideal for cards, as I can just go down-down-play, or up-play, etc. But it makes healing in general much easier, as I'm not constantly juggling targets, I never hard-target anyone other than the tank who is top priority.