For PVP - Whitemane and for PVE - Mankrik or any of the servers linked to them. There are free transfers from other realms to these two servers that are already connected to others. The list of the connected realms is here:
The free transfers have been active for quite some time and they may be considering further consolidation once the seasonal server is shut down and anyone wanting to preserve their character from the Season of Mastery will migrate to an Era server/s yet to be named. It’s a good bet however that Whitemane and Mankrik will be the destinations.
Good luck to you.