it seems the obvious answer would be in scheol or adonis, however:
seems that alot of people group in elysium up until about 150, then they vanish. scheol is always empty, and in adonis, people are looking for players 190+. maybe it's been my bad luck, but after i reached 160, i have not been able to find one group in the shadowlands, and i've been lfg at different times of the day, spread across several days.
where have you found good spots to group up in between these levels besides rk missions?