IMO every single game ever.
Don't get why people would want to watch someone else play a game when they could be playing it themselves. Exception for games that aren't yet released though since people might be interested in seeing what it's like. But once is has been released it just seems silly to watch it rather than play yourself.
Well there is a few reasons I can think of that make sense to me
1. Speed Runs. Because you can fuck off if you think I have the time or dedication to do this myself but some of the shit they pull off is crazy interesting.
2. Competitive games can be just like watching sport, and we dont go telling people to just play the sport instead of watching now do we. Or they could be trying to get better at the game by watching the way pros play and the stategies they use.
3. The personality is interesting, there are some people I watch regardless of the game they are playing. Im not always there for the game but the commentary.
4. Its a game you will never play, such as my brother and TLoU... Ok I still think he's an idiot for ruining this one. He could have just borrowed my PS3/4 to play it -_-
5. I need to sleep =P Yeah I often fall to sleep doing 1 of 2 things, listening to a podcast or listening to a Twitch stream