This is basically the age-old question between DPS and Alpha. In a game called EVE Online, there are (broadly) two types of guns: those with a high sustained Damage Per Second on average, and those with a HUGE amount of damage per shot (Alpha) but that then take 30 seconds or more to reload before firing again (meaning that when you average it out, their DPS is pitiful).
So should you aim to have 1.4 arrows-per-site, or 3 wounds on a single minion on maybe one or two sites before dying gloriously? Answer is of course "it depends".
In EVE, the answer is almost always to go for the high
DPS, with one exception: if you are in an organized group with support. In such a case, a single fleet commander directing 50 people to all point their artillery at one target will turn that target into paste before they can even think about calling for repairs. Who cares about a reload time when you only need one shot?
Likewise,
Greenleaf shines when you set up the support structure to give him regular heals.
Elrond, Herald to Gil-galad,
Galadriel, Lady of Light,
Frodo's Pipe, and Tale of Gil-galad can all keep the one-elf gatling gun shooting. Once set up, the question then becomes "do I want 1, maybe 2 indirect wounds; or do I want 3 directed wounds whenever I want, and 1 indirect wound when I don't." Who cares about being exhausted when all the minions that matter are dead?
Greenleaf can also work as a splash companion when you want him to snipe someone and then also eat a skirmish. Imo
Son of Thranduil shines best when you want Legolas to actually fight and win skirmishes and the archery is just a bonus.