This isn’t painting the full picture. There are 5 NA clusters (+an OCE Cluster) for our Classic Era region. There are also a number of RP realms that exist as standalones without any realm connections. That said, ALL clusters + RP realms in our region are Cross-Realmed for Battlegrounds only.
The two most populated clusters are the PvE East (Mankrik+4realms) and PvP West (Whitemane+9realms) because they have been designated to recieve free transfers.
Outside of the free xfer destinations, there are 4 additional clusters (PvE West, PvP East 1, PvP East 2, & OCE).
Sharing the bluepost about these realm connections/clusters:
OP was asking about PvE so their options would be the PvE East Mankrik cluster, the PvE West (Atiesh, Azuresong, Myzrael, and Old Blanchy) Cluster, or the RP-PvE standalone Bloodsail Buckaneers.