Radeon RX 400 Series

Graphics Card - ATI Radeon - RX 470 - 8gb
Graphics Card - ATI Radeon - RX 480 - 8gb

How do I decide on which components are good or better than others ? How do I decide the best buys.

First and Foremost we can google the product we wish to buy and check it's reviews or what others experience about the component you wish to buy. You may also post your queries on any of technical forums and get replies from other users.