I doubt you wanted something long, but I'll give it anyway.
I've always been warmongery, though my plays don't always end with domination (I prefer just enough warmongering to basically ensure that other civs can't achieve their own intended victories). My main ventures into strategy games started with Starcraft/Warcraft and Advance Wars, so my interests in Civ are focused mostly on combat (though it's rather thin) and area control (which is quite a big deal in Civ).
1. Norway
It's tied with Scythia, but I'm very interested in seeing how much improvement Civ6's Norway has over Civ5's Denmark, and how much the improvements matter. The Longships having a coastal raiding ability will be fun to play around with. Efficient embark/disembark is what I'm most interested in; as someone who misses Civ2's air units actually being on the map and likes airships and hover units, this is about as close as it'll get for high mobility units in a mainline Civ game.
2. Scythia
Scythia's individual elements technically aren't new, but they're put together in a very exciting package. A strength bonus versus weakened units and restoring HP on kill will support opportunistic strikes that can develop into a nice big snowball. Will be even more fun with ranged units. Civ5 has precedence for deploying multiple free units at once, but those were restricted to wonders or tenants. Scythia can deploy a free copy of a unit (of specific parameters) each time to an encampment district, and I'll be very happy to take advantage of that. I'm hoping there'll be a policy that lets me deploy free copies of any type of unit in any time period to the city's encampment/harbor (I very much doubt this'll happen though).
3. England
Once again England has a nice naval movement bonus, and I usually like playing civs with good mobility. I'm somewhat curious about Sea Dogs; they seem to be Privateer replacements, which are normally melee naval units. But I think in the video for England, the Sea Dogs had a ranged attack, so I'm wondering if they capture ships at a distance with sentient cannon balls, or if they still have to move in and perform a melee attack.
There are other civs like Germany and Spain which I probably have more interest in over the other civs, but I'm too lazy to write up any further explanations.