As a very rough rule of thumb, heavier blades can tend to give better feedback than lighter ones, simply through having higher average density.
A good one-ply blade is probably going to give you the best low to mid frequency vibration (ie: playing feedback) of all... with thick balsa core blades providing the least.
Any blade that has a higher density wood core (above 300kg per cubic metre, such as ayous or Gabon/okoume) will also tend to give you better feedback compared to other lighter core woods (eg: Kiri or balsa).
Also, look for blades where the average density difference between each layer of wood is relatively small, as vibrations in a blade tend to have trouble passing from one material to another if the density difference between them is too large. You do this by looking up the average density for each species of wood in the sandwich, and look for a low range of differences between the lighter core wood and the heavier outer plys.