I've used some "generic" Blue Tak and also thought that it was "stickier". The stuff that i tried came from a graphic arts supply store but i don't remember the name.
As a side note, i think that all of this stuff will leave some type of oily residue behind it, so be careful when using it. You might end up with dark spots on your finish or paint if directly applied.
Other than that, try sticking a thin layer of re-bond carpet padding between the ceramic art and the wall. If you can cut the padding to the contour of the art, you'll never see it and it will damp the vibration from being transferred from the wall into the ceramic and at the same time, damp the air-borne vibrations that the ceramic pieces themselves pick up. You can probably get some scraps from a local carpet joint for free or next to nothing. Sean