I'd start by trying the guilds listed in the progression thread
. I primarily play Republic, but I know that Shades of the Eternal Void
are the two best Imperial PvE guilds. Their main groups are pushing HM Terror From Beyond right now, so I'm not sure how much focus they're putting into EC, EV, and KP at the moment, but if you're looking for a solid player-base, you can't go wrong with either of those guilds.