Igris vs Tengen, in terms of dmg, aren't very different. Igris does a little bit more than tengen, while tengen has a little bit less spa than Igris. Like you said Igris is a boss killer, so if we include the 25% dmg buff, his dmg is far more than Tengen. But Tengen does get full aoe faster. However, most modes' hardest part is the boss so... But Ig Tengen takes it as he's a mythic while Igris is harder to get. But I'm curious about gojo. He is the highest DPS unit as of right now, but he isn't good for progression. His full aoe takes ages and he's single-hit, making it harder to do story. And you can only evolve him after you reach shibuya inf. So, is he there only because he's the highest DPS unit? If so, then Igris and Tengen comparison is a bit messed up.