+1 on the RPi3. If you want to replace the WD Live, it'll do fine.
However, I found it struggled on h.265 encoded video @ 1080p. It also couldn't run tvheadend with my USB TV tuner; it either worked but missed frames or just gave a black screen. No amount of google-fu or re-installation from scratch seemed to resolve the issues. Netflix and Amazon Prime don't (didn't?) work with it either. That's when I switched to a x86 compatible system for 3x more money.
Also the x86 system allows me to have storage right on the system as well.
ers