Solo pve - troll unguent. Instance runs - healing spring.
The Troll heal is amazing in PVE, since you can mostly control the incoming damage (manually controlling your pet/kiting if at all necessary), and most of it isn't spikey at all. You can also make this work when you're in a WvW zergfest.
The Spring is perfect for most boss fights, since they are stationary, or don't move fast, nor a lot. With the cripple and chill from the axe and shortbow, I can even manage to kite within the circle. It almost heals as much as your default heal, but the added regeneration (it's not a HoT) and cleanse is very nice indeed. Also, it does combo!