I've been playing the Civ series since Civ2 and one thing is I would never ever call Civ5 a perfect game or even close. It was infact a disaster until the expansions which made it alright but most Civ fans still prefered Civ4's gameplay to Civ5.
Civ VI however looks cool but has some serious flaws. The AI for one is absolutely terrible at a whole new level. If the AI goes to war on you which they most certainly will unless you have them scared and you take a city when peace happens the AI that attacked you will think your a warmonger as will the rest of the world. The AI will break promises no problem at all and there isn't anything you can do about it other then war which will make everyone else hate you as well. Ghandi for instance will flood your civ with his religion and no matter how many times he promises to stop he will keep sending missionaries and apostles which you can't even attack except through your own apostles. As far as the UI building units and research I'm currently in one game at year 1800+ and am in the industrial age myself playing on normal (prince) and the AI is running around with warriors, battering rams, and crossbowmen as their most advanced unit for most of the AI's. This is due to much of the AI being focused on either mass military or mass religion vs city growth. It feels like they don't want to get higher units because they can't churn em out as fast.
Then of course how the AI hates you so. They hate you for not having their religion, not spreading your religion, having a different government, having more wonders, not making enough money, not expanding as much as you should, making friends with city-states they want. Pretty much in any game 3/4 of the AI will hate you, 1/8th will just dislike you, and the other 1/8th will be neutral or occasionally like you.
One major mistake they made with Civ 5 that they repeated in Civ 6 as well is religion. Many people want a way to turn it off and when it first entered Civ5 in expac people wanted it was often hated.
I think you are coloring the world in your own view. I've been playing CIV since the original and Civ 5 was a better game than 4, even at launch. The Unit stacking in CIV 4 was horrid and thank god they got rid of it. Before CIV 5 the sole military tactic in the game was to bundle up all your units into one stack. It was incredibly stupid.
"The AI for one is absolutely terrible at a whole new level"
The AI of nearly every CIV game has been poor at launch. I remember playing CIV 3 the day it came out and the AI was the worst at moving it's military.
" If the AI goes to war on you which they most certainly will unless you have them scared and you take a city when peace happens the AI that attacked you will think your a warmonger as will the rest of the world. "
I played my first entire CIV 6 game without one war. It depends entirely what civs are on the map. In my 2nd game Pedro II tried to wipe me out during the ancient era. FYI you do not get a warmongering penalty if you are declared war on. You can be labeled a warmonger if you commit atrocious acts or declare war on others.
"Ghandi for instance will flood your civ with his religion and no matter how many times he promises to stop he will keep sending missionaries and apostles which you can't even attack except through your own apostles."
Actually if they do break a promise you can go to them in the diplomacy menu and declare a formal war under the reason of a broken promise. Doing this will eliminate any warmongering penalties.
"As far as the UI building units and research I'm currently in one game at year 1800+ and am in the industrial age myself playing on normal (prince) and the AI is running around with warriors, battering rams, and crossbowmen as their most advanced unit for most of the AI's. This is due to much of the AI being focused on either mass military or mass religion vs city growth. It feels like they don't want to get higher units because they can't churn em out as fast."
That's only the city states that do that. I've been through multiple games and the actual CIVs always produce modern units.
"Then of course how the AI hates you so. They hate you for not having their religion, not spreading your religion, having a different government, having more wonders, not making enough money, not expanding as much as you should, making friends with city-states they want. Pretty much in any game 3/4 of the AI will hate you, 1/8th will just dislike you, and the other 1/8th will be neutral or occasionally like you."
It sounds like you are just trying to play your tried and true strategy and not actually adapting at all to your surroundings. You can see each civ's agenda in the diplomacy menu. You should read it, it tells you what they like, don't like, and what they are trying to do. Of course Ghandi is going to be mad at you if you go around killing everyone and of course Spain is going to chastise you for not being their religion or if you are spreading a competing religion.
"One major mistake they made with Civ 5 that they repeated in Civ 6 as well is religion. Many people want a way to turn it off and when it first entered Civ5 in expac people wanted it was often hated."
What this sounds like is that you don't factor religion into your strategy and would rather just turn it off so you can keep doing what you usually do. Instead of complaining about a feature of the game how about you try to use it. Religion was a great addition in CIV 5 and they made it even better in 6.