Gravs get you fucked up the most I think. Even if you smoke a full 3g blunt by yourself, I bet you could get just as stoned by taking 1g of hits from a gravity bong. I've packed such small bowls and gotten huge hits from gravitys, used to be 1-2 and I'd be done. Still is about the same, but fatter bowls and maybe 3-5 hits if I wanna be stoned longer.

While any other device I find 10 hits to be equal to 1 good grav hit.