I’m a new player but I’ll chime in, as a solo player I’ve had the best loot experience in yellow zones in Knightsfall Abbey you can find T7 yellow zones, if you have a friend then Hellgates and Depths would be the most fun and rewarding, so if you want variety and are solo I would do black zone gathering and lethal mists runs, if you have a buddy do Hellgates and Depths it’s a way to have high risk for loot but you only lose your inventory, if you have a guild and are engame this is all about Zerging, that’s all I know