Hi Menadore,
Ex Inferno might be the perfect fit for you. With 5 Raid teams and an very active Mythic+ community, there is always something happening online. A lot of members of Ex Inferno are WoW junkies like you, with multiple 120 alts.
you can find out more about the guild here: [H] <Ex Inferno> Community is LF You!
Message me on online or in Discord if you have any questions:
In game - Bodhí (the í is Alt 0237), b-net Bodhi#11669, Discord Bo#0122