If you're just learning to play Civ 6 and want a leg up in your first games, there are three civs that offer very strong advantages you ought not to ignore.
The Civ 6 community on Reddit has picked up on an analysis of civ strength by YouTuber FilthyRobot that breaks all civs down into tiers by power or advantages over other civs. The analysis focuses on whether any civ's advantage is both consistent and strong enough to be a game changer. It also specifies which leaders are the best choices for each civ.
The results may surprise you.
Best Civ 6 civs and leaders: Scythia embraces early game advantages for the win
The basic formula for the Civilization series breaks gameplay down into eras, with each era offering specific advantages for certain civilizations. Civ 6 has eight different eras, and some civs have devastating advantages specific to the Ancient era when the game begins.
The unique Ancient era ability that makes Scythia such a powerful civ is active immediately, but only if the civ is led by Tomyris (above). Her units gain advantage in battle against wounded units and also heal every time they destroy an enemy unit.
This makes Scythian units easier to return to full health, and they only become more deadly the longer a battle wears on and the bigger it becomes. Because this advantage is granted to Scythia immediately and lasts throughout the entire game, FilthyRobot ranks Scythia as the best civ in the game.
Best Civ 6 civs and leaders: Sumeria is no pushover
Sumeria's strength also depends on early game advantages, in this case revolving around a specific military unit. The Sumerian war-cart is a heavy cavalry unit that can travel four tiles on flat land. That means you can spread out quickly to deny the enemy territory or harass their weak, early game cities.
FilthyRobot argues that the war-cart is so devastating in the early turns of Civ 6 that Sumeria deserves a spot in the top three. It's also worth noting that Sumeria earns bonus rewards for destroying the Barbarian outposts that are more plentiful in the early game in Civ 6. War-carts can spread out and find those outposts quickly.
Best Civ 6 civs and leaders: Germany embraces industry for the long game
Germany fills out FilthyRobot's top three civs list on account of its tremendous production capacity. German cities have one bonus district per city beyond what population limits ought to allow. They also have access to a unique district type called a Hansa that provides significant bonuses to production.
This makes Germany a civ that targets the long game, ramping up its production capacity in the early and mid games. By the time a German player in Civ 6 hits the Industrial Age, they ought to be ready to produce a huge army of modern war units — you know, just in case, right?
The power list also specifies Frederick as the leader for Germany, for the additional military policy slot he grants. Policies can subtly but meaningfully change the way a civ performs in Civ 6.
Best Civ 6 civs and leaders: The runners-up
FilthyRobot's second-tier civs are Arabia, China, Russia and Rome. The Arabian civ has a unique Medieval-era unit called the Mamluk, a cavalry unit that heals at the end of every turn whether they move or attack or not. Russia has a unique Industrial-era unit called the Cossack, also a cavalry unit, that receives combat bonuses for fighting in or near Russian territory.
China, on the other hand, earns a second-tier slot for construction bonuses rather than military strength. The Chinese leader, Qin Shi Huang, can sacrifice Builder units to markedly speed up construction on Ancient and Classical era Wonders, and the advantage of owning a Wonder during the Civ 6 early game is huge.
Finally, Rome sits at the bottom of the second tier for its bevy of advantages. None of them are game-changing, but they do provide benefits consistently throughout the game. For example, Rome gets unique Bath districts that promote city growth. It also has Legions, unique units that provide strong city defense in the Ancient era.