I have returned to 5, as I just can't play 6 any more. Civ 6 has some strengths in it's early game, especially early district placement, but it becomes incredibly tedious mid to late game.
Civ V is much less micro heavy, its systems are much better integrated with each other (for example, other players actually care what you do in the World Congress), and there's more of a late game. You can also get the Vox Populi modpack, which will add a lot of new features, rebalance everything, and improve the AI a great deal.