ponychan - hugbox of manchildren in most boards
mlpforums - boring, tepid traditional messageboard
/pone/ - seems like a bunch of edgelords who ran away from 4chan because m-muh gamergate. arbitrarily ban anthro and off-topic but consider themselves FREEDUM
/mlp/ - it's alright. but somewhat stolid lately, which while sometimes a good thing, not so in this context.
mlpchan - /anon/ - as has always been it's description, a very nice board suffering only from lack of activity. /oat/ - tripfagging and circlejerkery and autism, but in a deceptively pleasant form unlike ponychan's version.
r/mylittlepony - a terrible mix of bland news, announcements, and people whoring their (or other people's) art
EQD - boring news site, comments section is akin to Youtube comments. mind-killing.
graveyard - equestriachan, fimchan, 7chan, fluttershy.us, r34pchan, canterlotunderground, dashchan, pony-chan, lunachan, etc etc etc