There are many options to farm Bounty Materials in Diablo III. These materials are very useful to extract items for Kanai's Cube and to create the strongest items in the game. For a full Bounty Guide you can check out this link. Below you can find an overview for the best builds for each different class:
*Disclaimer: Legacy of Dreams Wave of Light is the fastest bounty build in the game, but it requires exceptional gear as well as a "gear swap" while playing.