Best Karma Farm ??
Edge of the Mist gave me loads of Karma, it’s basicly a Champ-train on EU servers. Wouldn’t know if it’s the best though. I did a lot of low-level Fractals when I needed Obsi shards due to the ~6k Karma at the end and tokens for the Shards. Few of my guildies did Queensdale Champ-farm on 80s for their Obsidian Shards.
These are all the ones I can think of, hopefully someone has a more solid option.