Overall I like the pacing of this game, I think the colossi have a good progression getting more complex to fight and more dangerous. My favourites Dirge (10) Pelagia (12) and Phalanx (13) are bunched a little close together but after 1 and 2 I wouldn't say there's a point where two less good colossi are in a row. Basaran (9) is the only one I activly dislike fighting.

The one change that I'd consider making to the order would be swapping 13 and Argus (15). I don't think Malus (16) could ever be moved as that fight is set up to be the last in story terms. But Argus always feels like a low point in the end game. Especially as a human shaped colossus after a series of more interesting fights which I think hurts the pacing of the end game. Bringing him down to the 13th spot would mean that after him comes the extremes of the 2nd smallest/ fastest colossus (14) and then the biggest (13), it would also mean in my mind the best colossus comes right before the end, and importantly the 13th colossus is one of the best moments with Agro too, considering what happens in the end game it feels a bit weird that the final 3 fights all isolate you from your horse.