From the research I've read, and from personal experimentation.
The most efficient use is joints.
And the thinner, the better.

Big fat doobies are a waste of weed.
More resin get incinerated than inhaled.
Same with pipes.
The wider the burn, the more gets wasted.

The least efficient use is water-pipes.
Much of the active ingredient condenses when it hits the cold water and never reaches the lungs.

That said, I presently use a small glass pipes.
Attachment 278150
Because I have a surplus of meds, and I'm too lazy to roll anymore.

Aloha,
Weezard