Socialism For All is great for narration of audiobooks and speeches.

It's Called Leninism is a very promising up and coming channel with a historical angle.

Rathbone posts to YouTube alongside their TikTok content, so it's generally short form skits and observations.

Bad Empanada's main channel is good. His second channel and his other online presence is varying degrees of unhinged. People try to pin him down ideologically as a Guevarist or a Trot but this is false - he once stated that Stalin was 50/50 good/bad and Mao was 70/30, which is kinda astonishing because imo Mao made some pretty massive blunders while Stalin often made the best decision out of a range of bad options. He's very much opposed to Senderistas so he's either some variety of Maoist or the Mao 70/30 line may have been a subtle but very clear nod to him aligning himself to Deng Xiaoping. Tbh though I get more of a read from him as an eclectic Marxist than a Deng Xiaoping fan.

Edit:

Red. (@redstreamnet) is also pretty good, especially as a steady stream of news updates and On This Day In History posts. They also feature Lady Izdihar videos pretty regularly, and she's also another channel to follow.