I came to Overwatch eSports just from playing the game a lot on PS4 originally. I knew of eSports form spending some time in Korea and watching Starcraft and assumed there would be some for Overwatch knowing Blizzard's reputation. From there I discovered twitch, and the larger eSports world. I personally played a lot of CS 1.6 and COD MW2 before taking a break from any video games. Now coming back and finding Twitch and etc., I've watched some CS:GO and COD games and they are so boring compared to OW. I think the fast pace, and constant action of OW makes it be by far the best FPS to watch. Now I have no experience with MOBAs and so I know nothing about LOL or DOTA2, but as to the extent my knowledge base goes, I don't see anything competing with OW for excitement or joy of watching.
Much of this comment was influence by watching the most recent "Through the Grapevine" episode. Thoughts?