There are literally 4 GS players in BoRP. Veridian, Arete, Boom, Tsunami. If you count Jerrika that's 5. Most of GS's core either quit or went to Maguuma and joined Mada.
There are a couple of HOPE players that still play. Me, Aditae, Takagi Chrome (that's his account name), Hyperballad, Star is now the leader of KEK, along with Daddy Div who was Ark driver.
IIII disbanded and most of them joined Agg who for one reason or another are convinced they can run power builds (spoiler: you can't) against the meta. You legitimately MUST run the meta (celestial shout reapers, celestial mercy guardians, condi rev, minstrel tempest, power zerker, staff thief, mesmer) in order to stand a chance when fighting a guild of even skill. Also, IIII was what most would consider the current incarnation of EP.
The top guilds right now are KEK (FUN/Ark/HOPE conglomeration) and BoRP (Woe, a bit of GS, and a bunch of EU players). Below them is probably GS and BnR. We (GS) stomped SF and OnS in roster v roster and RISE has dodged us in 15s but have beaten us in RvR, although they run significantly larger than us. Everyone else is more or less in the same tier and can beat eachother depending on who plays better that night.
In terms of open field, VR is probably the best on NA due to the fact they run specifically for open field very well.
The top 3 servers at the moment are Mag, BG, JQ. BG is probably the largest at this point and JQ is the weakest of the 3. Mag's playstyle is extremely annoying to face.
Another thing you might like is that ANet has added a way to track KDR of servers you can epeen harder