Software developer and a novelist
Trespasser by Research Indicates is honestly so well written that it feels like director’s commentary rather than a let’s play.
Bobbin Threadbare’s Deus Ex. It’s half let’s play, half a series of lectures on various topics relating to the game.
For me a good let’s play is about the game and representing it, not about about the personality doing it.
La-mulana. It’s one of those games that only has value if you play it blind and without a walkthrough. The game’s platforming and combat is subpar at best and atrocious at worst, but the riddles and the mythology make up for it. I played it around 2008 on the “MSX” freeware version, and it took me 10 months and 2 new save files after getting stuck. You have no chances of completing that game without extensive notes.
Or a zip package signed by the developer.