Another vote for LFS. I like that it is really at the right level of depth (assuming that you already have a basic grasp of computing in general). Even if you end up going with a distro, reading through LFS gave me insights as to why certain things were done in certain ways. Alot of “quick-start” style guides tell you what command to type in, but for brevity reasons, they don’t explain what the command does. For example, you may come across many guides tell you to type sudo or sed or echo or | or >>. It may seem daunting at first, but gradually as you become more at ease with the CLI, all these will start to make sense.