Ah, the old "You don't share my opinion you must not play deity" retort. It seems to be a favorite around here. I do play deity and I've won too.
Sorry, I didn't mean it like that at all. I try and avoid ad hominem and the comment wasn't meant that way. I only meant that I'd fully agree something like the Keshik is crazy powerful when you can run from city to city sniping units on the way. Once you start to get walls of unit spam, the Chu really starts to shine, because like I said earlier, it is essentially two units on a single tile which is very powerful in a 1UPT game.
Once space gets cramped, which I find very common in Civ 5 (I personally think 1UPT would work way better if maps overall had more space and minimum city distance were farther--mounted units and chariot archers would actually have a use then), then a lot of the perks of the other 3 units diminish.
Another way to word it is how much firepower you can direct on to a single tile. Since Chu's attack twice, once they are in place they double the amount of fire. Longbows can bring extra fire by adding in a 3rd range, although it depends on terrain. Keshiks/Camels can add more fire by hit and run micromanagement, but that is also dependent on space and terrain.
I actually haven't yet determined what I think should be the winning unit on the list. All I know is that Chu has a nice set-up: Extra gold from paper makers to support them, a lot of experience in mid-game to stack promo's, and still continue to be useful in end-game when they get an additional 15% combat along with the massive stacked promo's. The difference of 18 to 20 strength is negligible. Good on offense and defense.
If you don't clear the map with Keshiks, you are stuck with a garbage UA and a not-as-useful upgrade. They are a one-trick
pony horse.
Camels are in a similar situation, but at least they have OP bazaars and a UA that supports late-game play.
I cannot really find any faults with England. They have two solid UU's and the extra spy is actually very effective if you consider the gap between the first spy and when you can pick up a second can be a very long time. Longbows are no artillery gun, but that doesn't matter too much. They can still rack up some promo's and are guaranteed 2-range Gatling, which keeps their "how much damage can I stack onto a single tile" strategy going, while Chu's need to level up to keep that advantage.