I guess that Taylor Herbert, as protagonist of the series, is a pretty straightforward choice. At least early on in the series, when the scale is smaller. The ability to control bugs and creepy-crawlies isn't a power with immediately obvious applications, so there's a lot of creativity in how it gets used through the series.

I will say that I think that her being the protagonist tends to have made Wildbow explore ways in which those powers could be creatively-used more than other characters, and that you could probably do that for a number of other characters, but there just wasn't the space to do so.

As a character, I think that Dinah Alcott, the precognitive girl that Coil keeps captive and drugged, was probably an interesting character. In a lot of the story, a character's influence is largely tied to their powers, but in Alcott's case, Coil figured out how to control her and exploit her powers. I think that if one were going to seriously do worldbuilding with superpowered humans, that it'd probably look more like a system of hierarchical structures where people who are extracting benefit from use of powers are not necessarily the ones who personally possess them. A dictator in our timeline isn't the physically-strongest person out there, say --- they work to maintain control of a military and security structures that incorporate people.

EDIT: Oh, yeah, and Dragon. It's interesting to see sci fi examining the "how do humans try to control these powerful AIs that they have built" stuff, and IIRC Dragon's the only AI in the series. I don't think that it's necessarily the most-realistic portrayal of what an AI in that situation would look like, but it does explore the friction associated with humans imposing constraints on an AI to try to keep it under control.

EDIT2:

As a launching point, what’s your favorite endbringer and why?

Honestly, I don't really like the Endbringers. I think that one of the worst enemies of long series, especially ones with magic or sci-fi, is "power creep", where every story has to top the last in scope and power. At the end, you find yourself increasingly painting yourself into a "save the universe" corner. Stories have a conflict, and the more-powerful the characters are, the more-limited you are in what that conflict looks like.

The Endbringers are powerful, so they escalate things a lot.

Also, I don't think that they're the most-interesting characters. I think that the antagonists that are more-interesting in the series have more-complex sets of motivation.

mostly as an outlet for all of the books I want to talk about *because I don’t have any fellow book fans in my friendgroup

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