I read from few pages here, there are some names mentioned eg minix or himedia or raspberry or acryan or mii etc but no comparison made for performance etc., some require rooting and flashing
android devices progress by leaps and bounds every year, even 6 months.
simplifed, the progression has been:
android: version 4.1 jellybean->4.4 kitkat->5 lollipop->6 marsh mallow
chip: dual core->quad core->octa core
memory: 1gb/4gb->2gb/8gb->2gb/16gb"powerful" generally = most expensive and newest.
the "most powerful" box at this time is probably an octa core 2gb/16gb lollipop 5.x.
the trouble with this "most powerful" is there are a no. of apps that do not support the chipset or the android version. in fact, most local iptv like astro-on-the-go, hypptv everywhere, iflix, etc. won't work with newer sets. can say they can't catch up so quickly.
so, why u want it to be "most powerful"?!
it all depends on how u will use it. for light users, a simple basic one will serve the purpose.
some will look for large memory to dump in all sorts of apps and never have to clean up.
some look for 3D, 4k and hd audio handling.
some look for proprietory apps, pre-installed apps, even iptv subscriptions.
do read this thread from page 1. don't get the idea that by buying the most expensive box, all will work well. not at all. becos these boxes are software driven, u need to know how or get help to make it work well.