Wonderful, thank you! :) <3
There's some debate in the Discord among fans which order is the best, but as a developer I've always made it a priority to make sure that you can actually jump in anywhere. Your perspective will be different, but they're all possible starting points (and they're all connected and in the same universe).
As the creator, I'd probably recommend playing them in the order they were made, which is:
Pitstop in Purgatory > The Painting > Ezrebeth (A Holiday Mindfudge) > Poetry in Purgatory > Guidelicious
But there are people who say that The Painting is better to start with, and even a couple who started with Ezrebeth and found that to be a cool way to be introduced.
And of course, Poetry is Pitstop's sequel, but since it's standalone you can also start there and that will make Pitstop sort of an origin story for you instead.
So any way you want it is fine, basically! :) <3