I have an aggressive fondness for Loopstuck (https://mspfa.com/?s=50209&p=1), it is just so charming to me with how you can see the authors art evolve over the course of the story, even if all the characters are insanely hard to remember and keep track of.

In terms of which one I think is the best written, I would say Fearn0t (https://mspfa.com/?s=31244&p=1). The art is so good and the story is so interesting to me! It's on hiatus rn but I really hope it picks up again at some point, I'm dying to see where it all goes.