Sacred Shield is the go-to answer if you are constantly being dispelled. The buff portion cannot be removed, only the absorb shield that pops up every 6 seconds can be.
In any group setting, when you are not a focus target, selfless healer will be a ways better than the other two choices. Again, the only exception would be if you're getting chain dispelled, in which you'd just lose your Selfless Healer stacks the second they pop up. This is quite rare of course, where you are not the focus target, and still getting spam dispelled. In a situation like this, sacred shield is better again.
In any solo situation where dispels aren't an issue, Eternal Flame is best with the recent buff to heal for 100% if casted on self. It is essentially a second wind, easy to keep up at all times, and the healing easily outpaces Sacred Shield's absorb. It loses some of it's strength when fighting classes with Mortal Strike and against DK's necrotic strike, but is still very powerful.