Guild Wars 2

I feel like a single discipline banner is more efficient than all spirits together.

If you want to make spirits any usefull you need to radically change them and not only make some little tweaks.

Some suggestions:
1. Make the percentage to activate the spirit buff on hit to 70% without traited
2. Remove the Spiritual Knowledge and add some other trait which increases the granted buffs on spirits (examples: raise Frost Spirit to 15% damage, Sun Spirit also gives weakness paired with fire)
3. Add to the Spirits Unbound trait to make them dodge when you dodge, because nothing sucks more than a spirit that dies by every AOE in a boss encounter.
4. Storm Spirit: throw away the swiftness and add confusion apply.
5. Stone Spirit: throw away the quicksand and add the special ability to create an projectile reflecting shield.

If you increase the spirits by far, ranger may be a option to give strong team buffs.

They could just increase the AoE of the buff to 3000-3500. Even with so-so buffs they would still be useful and mostly out of harms way the whole time.