I am of the opinion that in most ways, Civ VI is a straight improvement over Civ V. Unique city states with envoys are significantly better than the generic city states with declining influence that are in Civ V. Global happiness should be sent to the darkest pit that can be found and left to rot there; amenities and housing is a much more welcome return to Civ IV style city placement. The terrain actually matters now in Civ VI. In V, one can place a city basically anywhere and have it grow without issue, with more or less the same buildings placed within it. In Civ VI, every city is a puzzle; which districts and wonders are available to me and which benefit me best? Governors allow further specialisation, loyalty means I have to be wary of border cities and too much conquest, environmental disasters constantly change the playing field, policy cards allow for a flexible government (though I feel there are too many, and some are clearly better than others. Still, far more interesting than just unlocking five levels in Tradition every game). I can improve or harvest resources. I can use culture bombs to steal land. I can levy city state units and open up a second front for a war. I can enter a golden age and peacefully convert my enemy's cities. With all of this, Civ V seems very barren and devoid of actual empire management in comparison.
That said, there are some annoyances that upset me. I'm not a fan of agendas. On paper they sound great, in execution however they generally result in annoyance and seem nonsensical. I read somewhere that agendas correspond to leader abilities, and they will generally dislike you if you hamper their abilities. This, again, seems logical. Why, then, does Trajan like me if I have lots of land? He's a land grabber, he should hate me for stealing land! Vi's World Congress is a bit of a stinker and the lack of meaningful late game content like ideologies and corporations can be felt. That said, most of my complaints can be mitigated with mods. I've nodded the WC to start in the industrial era, leader agendas to have only a minor impact on overall relations, and filled the unit gaps with some extra units. Real Strategy also helps the AI plan their game more effectively.
Vox Populi is a wonderful Civ V mod but I don't know if I can go back to it now. Civilization V was a total disaster for me and completely unplayable. It took VP to make it enjoyable. Civ VI, meanwhile, I can fully enjoy with only a large handful of relatively minor mods. I think that sums it up for me.