The RP/PvP guilds I know with recent recruitment are:
The Blacktusk Clan (Horde) - Contact Silentfang, Héroya, Gungamwolv or Nazgob in-game
Quickfuse Cartel (Goblin) https://us.forums.blizzard.com/en/wow/t/h-quickfuse-cartel-goblin-guild-rpwpvp/1989402
The Redscar Legion (Horde) <Redscar Legion> NEW Horde RP/PVE/PVP Guild
The Sunfury Battalion (Blood Elf) [H-RP/PvP] The Sunfury Battalion Calls - Recruiting Blood Elves!
The Solarian Legion (Blood Elf) - Contact Shyrax in-game
Other than this list, I also show the following for the past year: Bladewind Legion, Hand of Tirisfal, Bloodtotem Exiles, The Duskwatch, Blood Crows, The Thunderhoof Clan and Hand of Algalon. You can also look for the FLAK! forum post. They’re quiet currently, but I would expect them to gear up again soon for Midnight.