I've heard multiple simmer youtubers say that let's plays don't do as well anymore, but I think it largely has to do with how they do it. I wish there were more, but I'm also super picky with how it's done. I don't want to just watch someone hit record and play for 20-30 minutes, I'd like a little bit of the dull moments cut out. Also, they tend to start out strong with giving their characters backstories and stuff, but fall off quickly by forgetting about it.
I like Fantayzia's LPs, especially her Modded one (her Snowy Escape one is good too). She gives her sims backgrounds and personalities and she sticks to them. Whenever the game tries to take control, she works it into the story in a way that makes sense and is realistic to the sim's personality.
Aside from that, I do like discussion videos. Like, "Here's what's wrong with/missing from the game and here are some ways they can fix it" type of things. The bigger simmers are all builders because that's the most fleshed out part of the game and since the devs know that, that's where all the attention has gone to with packs and updates. I'm not a builder, so build videos aren't really my thing.