I’m aware that the answer will always be situational, but I still enjoy this particular discussion. One comment I would add to my general question is that I am surprised that Ballista Elephants are not more often suggested as a best possible UU, since in most of the games I play with/against Khmer, they shred everything with seemingly no counter.
I do have a theory as to why I don’t see them mentioned in these types of forum discussions: Essentially, I am only a beginner and as such only play people with fairly low ELO (always <1000), whilst I assume that most people on here are probably >1000 at the very the least. Given that low level games tend to have little initial combat as both players get to castle/imp, this allows more opportunity to mass Elephants, at which point - say when you have 35+ - there’s nothing that really can be done to stop them. On the other hand, high level games are never as tranquil so it’s harder to achieve the critical mass at which they (seemingly) become unplayable.
Low level players will probably also prefer them because they don’t really require/aren’t capable of particularly delicate micro - unlike say, plumed archers or mangudai, which are consistently offered as best unique unit candidates.
Am I just missing a counter strategy that only higher level players use, or are they really as strong as I think?
The reason why most people don’t say its the best UU is its vulnerability to conversion in low numbers, high cost to mass enough in a reasonable amount of time and limited mobility. Like you’ve mentioned it yourself these might not matter much in lower elo games or in maps like michi but it does in standard open map games.
At higher elos, only a few unique units can work. Gunpowder unique units, fast unique units that naturally become the main army of that civ, slower but cheap unique units which complement the main army of that civ. Rest are either too difficult to go for, cant get much use by making them or don’t have a purpose and are too niche.
For me the best unique units in a standard RM 1v1 open map are Conqs, Leitis, Coustillier, Mangudai and Huskarl. And in closed its probably Janissary, Organ gun (not sure about the new one), Conqs, Arambai and longbows.
I tend to favor the Throwing Axeman. It does not have the raw population efficiency of some units, is less shiny than others, but it compliments its civilization’s needs well. It also allows for eclectic builds that can be strikingly effective.
That said, they have some rough competition with units that are oft more straightforward.
PS This is not a popular view