Biggest as in size/resolution, or biggest as in the most work? I think either way, mine would be this one at the moment from back in 2017. I worked on it off and on for about two years, figuring out the composition (which turns out to be a trapezoid tilted sideways, though it could be a simple triangle if you ignore the staff). The most time consuming was translating their outfits properly (which were designed by real fashion students). Looking it at it now in 2022, I see all kinds of anatomical flaws and details I have forgotten (like the blue tips in the green hair). :
It’s my favorite so far, despite the fact that I’m totally changing up their designs to bring their story to life in a way that allows me to draw them faster.
I just answered this one in number 2, but yes, I’m going to be drawing them again in the future.
I’d like to be an artist-writer fusion, as I work on improving both crafts. Wish me luck.