What civ do you consider the most overrated? The most underrated?

Overrated

For me, I have this weird relationship with the Mongols where I simultaneously hate playing against them, but I also hate playing them. I think it boils down to the fact that if you play the Mongols, you will make Mangudai 100%. This makes the civ extremely predictable, and because Mangudai are so expensive to upgrade fully, it means they can take a while to get going, which could be too long.

I feel the wins or losses of the Mongols depend entirely on how well they mass their Mangudai, since everything depends on having a threatening mass with a constant presence. Players who neglect the Mangudai will lose, those that keep them alive will win. As such, all it ever takes is ONE solid Mangonel shot and it's an entirely new game, so I'm not sure how great the Mongols actually are when they're so heavily and obviously invested in one unit type. When facing someone who knows how to take care of their Mangudai though, it's admittedly very frustrating.

I think the Ethiopians are also worth mentioning. This civ I don't have a problem with and I actually enjoy playing them, and I can do decent with them. However, there's no denying that Ethiopia has a very disappointing win ratio in their tournament appearances. This could partially be due to Empire Wars having bias towards cavalry, but iirc their winrate in KotD wasn't great either.

Ethiopia isn't so much a civ that I personally think is overrated, but I also think we need to acknowledge the statistics suggesting as much.

Underrated

Byzantines are a civ I consistently hear people say "they're actually not that bad" to, and I'm really unclear on why there's any debate on if they're good or not. In any given game, you can expect to encounter either cavalry or archers, at which point you are saving 25% on all trash units made to counter them. Their tech tree is also absolutely ridiculous; if it had Blast furnace it'd have "everything" except for siege.

I also feel like Larry has shown the Magyars are underrated. At the very least, I can't be the only one that considers Magyar's late game absolutely broken. Hera's late game strat has become "spam Hussar" and the Magyars do that, but better, because their Hussars trade decently when they're forced to fight gold units. The Magyars simply demand pressure, but as long as you can break down any potential walls, it's a very dangerous civ, both in the early game and the late game.