i love aus but my preference with writing will always be canon comp.
this is just my own opinion, but i write svt fics because im so intrigued by the dynamic they have with each other and who they are as people and i love to explore. and as much as i do love an au (my first two fics are aus) there's something about canonverse that i think hits different; these dynamics are at their most potent. i also think there's more potential for character study type of fics in canon comp fics which is something i love writing. there's also the more behind the scenes fics where you can build off a moment that happened and satisfy that lil fushoji parasite (one of my favorite canon fics builds off the haoshua kiss in a live) or explore what a relationship progression can look like with someone who is your coworker and friend where there's so much responsibility on the line and the naunces of that (there's a brilliant soonhao fic that explores that) or even piece together canon moments together which i got to do with beta cancri. it's also really infromed by how i watch svt content? like so much of my fic ideas happen when im watching gose or in the soop and i get inspired! also the worldbuilding element, i really love being able to reference certain moments and details much more than building an entire fictional world in an au. moreover i enjoy doing ensemble scenes and i think the (platonic or even more) dynamic of ot13 is near impossible to replicate in the same capacity in a noncanon setting.