Wanted to add to this. Leech does have some additional benefits outside of healing from damage. It also heals you based on any healing you do. Sitting at about 21% leech right now, mend pet over 10 seconds heals me for about 20% of my health with animal companion (since it is healing two targets). Exhilaration will also heal you based on the heal to your pet(s) in addition to the 30% heal.
Personally, I just use a clefthoof at all times due to turning mend pet into a short semi defensive CD and making exhilaration basically a full heal to myself. I also have bloodlust ready if need be and if the tank is taking too much damage, clefthoof can tank a single mob briefly without dying using growl.
My personal preference anyway. Good post overall 