Tough cookie, I tried Binding Heals, and it’s good so far. I also tend to pick that 50% self heal bonus power, but obviously new season will start.
I’m just not sure about using it instead of Guardian Angel, esp. because of that 60% heal, this usually is enough to save the Guardian from being used, so you can use it more.
Binding Heals for a raid, Guardian Angel for M+ is default pick. If you are more into PVP, Guardian Angel is perfect fit for Arena while Binding Heals works better in BG / RBG.
Guardian Angel might help occassionally on progress raids too, e.g. it might help to bump up Seeds on Prototype Pantheon more easily as you can throw wings every 60 seconds. When you have better gear tho, I would go with Binding Heals on that boss as well.