This is a post-fall patch tier list for civ 6. After the winter patch, going super wide was nerfed a little, and you are no longer able to rack in the bonuses of 10 powerplants extending their bonus to one really over powered city. However, you get the basic idea with this list:

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

God Tier:

1)Germany

2)Rome

3)Greece (Gorgo)

 

Strong Tier:

4)Sumeria

5)Russia

6)Arabia

7) China

8) Greece (Pericles)

 

Average Tier:

9) Aztec

10) Kongo

11) Egypt

12) Scythia

 

Below Average Tier:

13) England

14) India

15) Japan

16) Brazil

 

Weak Tier:

17) America

18) France

19) Spain

20) Norway

 

 

In single player, the game is not focused on military victory as heavily. However the AI will try to attack you early on, and if you are not careful, barbarian horsemen will raze your city by turn 30.