I started with LaTeX back in the day, but it was too hacky and complex, so I went to ConTeXt, which felt more consistent and planned out. Then I did OpTeX for a while and eventually I picked up the TeXbook by Knuth and it all just started to make sense to me. So now I use plain TeX with my own macro file to fill the gaps in functionality, I implemented colour support and picture support and small macros that I needed. I am very much into grid typesetting, so I need to know where all the vertical material comes from. There are areas that still scare me, like modifying the output routine or several \expandafter in a row, but usually that’s not needed. With plain TeX I can know every detail of the code down to the primitives. Of course this is possible in LaTeX too, but, there’s just a lot of code, layer upon layer, and I’m not smart enough to keep all that in my head.