Are you me?As stated, it's a matter of taste, but the Civ V art Mod and Tsunami Waves Lite make the game look 101% better to me and are just about required for me to enjoy the game at all.
After that, Faster Starting Settlers and Extended Initial Vision make up for the generally execrable starting positions and give a bit of 'nomadism' to the start of the game.
Are you me?
That's pretty much exactly what I would name as my "must-have" mods. There are several others I like, such as Terra Mirabilis for example, although that approach is probably not for everyone.
Quo's rocketboots. Adds +1 move to all units. I've had it on from almost day one. Really alleviates VI's slow movement system.
Theres one that adds reindeer to snow and tundra that makes tundra spawns more tolerable. Sukritact also has a resources mod that adds a few flavor resources, like camels in the desert, without going as over the top as "resourceful".
There's a new one I'm trying out by Pokhiel that improves the encampment by giving it some adjacencies and a few other tweaks. Makes them more fun to build.
Also the one that gives you lots of info when you mouse over the leader portraits at the top (Better Diplomacy Ribbon, I think it's called?)