For me it’s the PVE part of Elder Scrolls Online (PVP can be more toxic). Everyone there helps each other. New players are always welcomed and can always ask questions. Guilds with people ready to help at bosses, dungeons, crafting, … Just a great community.
Also have to mention Deep Rock Galactic. Rock and Stone, brother!
The one that always gets upvoted in this constantly asked question, is Deep Rock Galactic.
Then someone says “Rock and stone!”
They do seem nice, though.