Advent of Code is fun! I have done it every year since the start. I have previously used C++, Rust, Racket, F# and a smattering of Factor and SML.

I'm vacillating between doing it in C# and Javascript/Typescript this year. C# has gotten more attractive lately as there are improvement that makes it less ceremonious for short programs, like toplevel statements and global imports, and also fun optimizations for ricers. If I do it in JS/TS I would do it in a web environment, and try to do it with a nice web GUI.