I am thinking to buy one of those to play local media flies onto my HDTV. But im confused which one of the two will serve me better? My main aim is to watch BDrip movies which i first download on my laptop/computer.
in that case, WD player is the best option for its widest media support and easiest interface.
asus models are also very good and cheaper.
There's an app called Videostream for Chromecast that you set up on your laptop (requires Chrome). It transcodes any non-native movie and relays it to the Chromecast in max 1080p (depends on the resolution).
I've used the Chromecast for over a year. It's a cheap, wifi-enabled HDMI streaming solution that works with many things!