I have a lvl 50 Sorc and Agent, plus a lvl 31 Merc. Having played all three healers, I think the Sorc is pretty easy due to the bubble and extra utility (e.g., force speed, extricate, CC any mobs, etc.) over my Agent. The Agent is all about micromanagement with having to watch your surgical probe, TA proc, energy levels, etc.
The 1.2 patch is going to mess with Sorc resource management from what I've read, so that may make them a bit less easy to play.