That all depends on what you need and your budget
eg. MKV off an internal HDD … do you you want H.265, 2K/4K support with that ok?
Do you need Netflix and other Streaming services ?
anyways plenty of discussion found here and on gOOgle … eg
Personally, i just needed H.264 Mkv, Mp4 and Avi + DD/DTS on a budget … so i bought a Raspberry Pi 2 running OpenELEC Kodi (Very Happy with it)