For me I really do enjoy watching some of the Locking picking lawyers content and he is an expert when it comes to picking locks!
Another few are mental outlaw (although I think everyone knows of him here) and Steven Bridges who makes videos on card counting at casinos and he shows how much he wins/loses from playing
Dank Pods - hilarious Aussie who messes with iPods and old mp3 players. Very entertaining
I like his automotive channel as well
Is he niche though?