PS3 is slightly! more expensive than an xbox1, and although it can decode 1080p h264 with ease, various formats will need to be transcoded for it. I don't think the ps3 is really comparable to XBMC for functionality though.
considering the cost of a second hand xbox, it can make a fantastic media center, which so long as you don't want HD h264 playback, will do a great job. (You can do 720p mpeg4 at ~5000kbit though if you want to transcode from h264 etc)
BTW the home for the xbox version of xbmc is now at
http://www.xbmc4xbox.org for those that are interested. friendly community/forum too.
