What do you need a letter for?
Pick whichever feels closest. There's no wrong answer. Letters in any theme are written for someone going through something hard.
Each letter on hopepost is written by a real person who has been through something difficult and wants to leave a small bit of hope for someone going through it now. Pick the theme that feels closest to where you are. There's no wrong answer. Letters in any of the themes were written for someone going through something hard, and they're often closer to each other than the labels suggest. Letters refresh on each visit, and you can save the ones that help.