With the recent addition to an additional stack of TA for the Medicine line, I find this rotation useful:
Keep Kolto Probe up on Main tank, O/T and the other healer. The ticks of that will hit for over 700 for me and crit for around 1300. In keeping that up on multiple targets, you'll almost always have 3 TAs up at any given time. For me, KInfusion is very useful when I can maintain the probes on multiple targets. Shorter activation, lower energy cost, and I've had it crit for well over 5k.
However, keep Injection ready at all times, because it is still the main used heal.