I am a big Counter-Strike: Global Offensive fan. I play a bit, but I vastly prefer to watch professional play. I got into the game a year ago or so, and that seemed to be a glorious time to spectate the game. Streams were virtually exclusively on Twitch, and every weekend it felt like there was a ($100k+ prize pool) tournament, and every week there were high quality pick-up/practice games between professional players being streamed.
Of course (who can blame them?), YouTube Gaming wanted a piece of this pie. They cut some exclusive deals with a couple online leagues and tournament organizer, bringing a sizable chunk of the content with them to YouTube Gaming.
However, the users DID NOT follow (and UX over on YT can be almost entirely blamed), and the ensuing fracturing of the community has seen CS:GO drop from consistently top 5 in Twitch games to regularly outside the top 10. The thing is, though, the missing viewership mostly didn't migrate to YouTube, instead just deciding to not watch at all. The appeal behind Twitch and CS:GO was that there was basically non-stop _very high_ quality content being streamed, and you didn't need to put in a single ounce of effort to find it. YouTube very much does not have that same user flow down, at all.
And now (even though the position isn't particularly degraded), owing to the relative difficulty of finding tournaments on YouTube OR Twitch, I find myself watching a lot less. So goes the general vibe of the community. Sure, woe is us, 2 whole sources? But consider this: YouTube's discoverability is horrible, its UI plagued with reruns emblazoned with a red "LIVE NOW" that screams for your attention at first and later leaves you unwilling to trust any visuals on the site; Twitch, on the other hand, with its inability to pause / rewind / stream a smooth 1080p60 (hell, even 720p60 stutters 10x as much as YouTube's) leaves you comparatively upset about video quality when you watch there.
So I guess my point is that Twitch clearly loses in the tech department to YouTube, but its benefits (more entertaining chat, better discoverability and UI/UX) are more than enough to make you a dedicated user when exclusivity is part of that package. It'll be interesting to see which side can overcome its issues to gain the advantage.
Note: edits for readability have occurred over the 5 minutes following the posting of this comment