Triumph is universially OP in aram

Are you a tank? Take this, because it scales with health and makes you harder to kill when you dive.

Are you a squishy? Take this, for some added protection from dives. Also allows you to make more proactive plays.

Do you have a strong early game? Take this to increase snowball with more takedowns.

Do you have a weak early game? Well, Triumph is still the best option, as takedowns will happen regardless. If you are like 0 kills to 10, then you're screwed regardles. You will likely have taken more damage from the other team and thus have more missing health and get a stronger heal.

Do you lack sustain? Take this rune, and you'll have it.

Do you have sustain or a dedicated healer? Heals doesn't have diminishing returns. More healing is always nice.

Will the enemy team have a hard time applying Griveous Wounds? Take Triumph to punish that.

Does the enemy team have multiple sources of Griveous Wounds? Griveous Wounds are an opportunity cost, so if the enemy team needs to have to counter a minor rune, when they could have different items and summoner spells, it's a win. Even a reduced heal can be significant.

Are you a champion? Well every champion needs gold. Take this to gain a bunch of gold for free. "but it's not free. Opportunity cost of different runes". The healing is enough reason in itself to take the rune.

NERT TRIUMPH NERF TRIUMPH NERF TRIUMPH