Would you be surprised to see a very long answer for each one? 😅
There would always be a specific aspect, a flavor or dynamic in each duo that stands out for me to love. And all Seungduos have the amazing quality of being distinctly special.

On a surface-level, it's definitely more like a favorite-of-the-day for me than an all-time favorite, but to make things simpler and shorter, I'll organize what I love in each duo into broader themes! (Update after writing: it was not, in fact, simpler and shorter. But imagine if I went EVEN DEEPER...)

Brotherly bonds: SeungI.N, SeungBin

These brotherly pairings make me feel so so warm and yearn for a sibling I don't have 🤣

Whenever they're around each other, they create their own little bubble of mutual mischief. At times they seem to really dislike each other, but only deceptively so. Its because there's this trust that the messing around they do will always just be messing around, that they can afford to get annoyed with each other so safely. When it comes down to it, the way they support each other goes unspoken, but palpable.
They will never be as openly sappy about each other, but it's all there in the undertone of their scant compliments.

Best friendship: SeungLix, SeungJin, 2min

So what differentiates the brotherly bond pairs from these best friend-like bonds?

I suppose... It's "provision" ?

There is a hand someone takes. There is care offered and care taken. There is trust to be cared for without asking for it.

Vulnerability takes many forms, and these 3 pairings have their own flavors of need and supplication. One is presence, one is openness, and one is understanding. And it's all a balanced tango of needing and feeling needed. It's these flavors of vulnerability that scratch an itch for someone who craves to care for others, and it's beautiful to see them fill and fulfill each other emotionally.

Absolute admiration: SeungChan, SeungSung

The gravity of the first 2 does not leave the last category with no emotional ground, however. This absolute admiration isn't blind to comparison to the self. But because they have the benefit of being together, they hold on a little tighter to what they can cherish. It's not even restricted to their art, of producing and writing and singing, but to the grit and discipline and dedication they lay down for their craft. And beyond the craft, even their lifeways, the way they carry themselves. They've both always admired everything about each other, envy without malice, jealousy without spite. It's so beautiful to me how they remain so genuinely invested in each others growth as artists no matter how much time has passed being together, what more how much it pushes each other endlessly upwards? It's amazing, mutual devotion like a laser bouncing infinitely between mirrors that they cut down what obstructs each other from their goals for themselves and for the Other.

So... Yeah. I genuinely cannot answer my favorite duo, because I wasn't kidding when I said there's very specific peak appeal to me in each and every one of the seungduos....

Im so sorry and also very thankful you asked because it made me put to words some feelings I havent had a chance to chew and reflect on. I hope... That was ok? 🤣