I'm very the same as you! I always most like stuff that feels like it could fit in as a deleted scene, could pick up where canon left off, or that departs from canon at some particular point but is still very knitted into canon. Most of the time I just want more canon-ish energy if I really vibe with something! That's especially true of writing. I really want to dig into what's there in the canon work itself.

I have occasionally read mundane AUs, but not very often, and usually I only get drawn in if they feel like they in some way share the same sensibility as the original text. (For example, I got very into an OFMD modern AU where Ed and Stede were rival picklers with pickle booths at a farmer's market, hahaha. Like, that felt right to me on a soul level.)