well,this is civfanatic after all,but from what i have seen in general streamers and youtubers just tend to go back to civ v or the casual crowd in general....i too just go for civ 5 mainly because i play multiplayer
Here's the thing civ 5 graphics,artstyle ,art direction,ui,little details and just general qol improvements and polish is far far better compared to civ 6 imo,but civ 6 do imo have better models and animations though sadly rest of it doesn't support it especially the shaders,lighting,textures and ui.....so partial you see mainstream still clinging to civ 5.
But here people can overlook visual of the games,civ 6 has by far more mechanics gameplay side of things,Problem is and i will get hate for it,More is less in this case,and the addicting gameplay loop has been lost for me in civ 6 for me,Partly because even though civ 5 has less mechanics and features(but still some features and gameplay stuff that civ 6 don't have..like united nations..etc)...
The less is better in this case because each mechanic is layer beautifully and gel togethers well,its balanced and just designed better in general..
But it wasn't like at launch at all for civ 5,that's why i had hope civ 6 in time will surpass civ 6 easily with lots of fixing but r&f actually made me fear more of civ 6 gameplay and design issue....unit imbalances,gaps in unit upgrades,dumb a.i,exploitve system district and linear card policy system(civ 5 civic tree was perfect with nqmod),happiness issues,warmongering to be the dominant playstyle,huge imbalances in almost everything and all these not supporting each other.
And that's it i am just really concerned about civ 6 future..
As for what to choose.....civ 5 vox populi > civ 4 > Civ 5 nqmod/bnw > civ 6.
just go with civ 5 if you are new to civ ,its the best game for beginner's most people i know just don't have the same itch for one more turn with civ 6 as they do with civ 5 bnw