I played some 4, but like 6 a lot more personally. A lot of folks still prefer 4. 5 I think feels like the worst of both worlds or a stepping stone from one to the other. The big thing I like about 6 is that citizens actually have to travel to buildings to work or use services.

In Tropico 4/5, a clinic may have a capacity of 200, so if your population is 350 you need two clinics placed anywhere, which I think makes city planning a little boring because you could just have a clinic corner where you build all your clinics as needed. In 6 a clinic has 8 visitor slots, and when a citizen needs healthcare they claim a slot and physically walk or transit across the map, enter the clinic, then spend some time there before leaving and freeing the slot up. This means you could build a couple clinics far away from each other so citizens have less distance to travel to the nearest clinic, or you could have one in your population center, but invest in making that building high quality so when a citizen leaves with a higher healthcare value it takes longer before they need to visit again, reducing the overall demand and making the visitor slots go farther.

It lends itself toward building actual neighborhoods where they are needed which I like!