YouTube Advantages: Works on a bunch of platforms such as Android, Apple TV, Chromecast, FireTV, iOS, Roku and smart TVs. Different resolutions to choose from. Able to rewind stream. Disadvantage: Currently do not meet the requirements to embed the live stream. Subscribe now and press the 🔔
Twitch Advantages: 3-7 seconds of latency with low latency mode. Best quality. Stream viewable in most mobile browsers. Chromecast support in mobile and desktop Chrome and app too. Lowest latency when using Chromecast. Disadvantage: Quality may degrade in low latency mode. ~3 Mbps due to no transcoding.
Mixer Advantages: 2-3 seconds of latency with FTL mode. Stream viewable in mobile browsers. Chromecast support in mobile app. Disadvantages: No Chromecast support in desktop Chrome, yet (just cast the tab and full screen the video). FTL mode requires app or desktop site on mobile devices. ~3 Mbps due to no transcoding. Mixer stream
Smashcast Advantages: Not being tracked by Google, Amazon, Facebook or Microsoft. Chromecast support. Disadvantage: ~10 seconds of latency.
Facebook Advantages: Lots of people on Facebook. Chromecast support (mobile requires app). Disadvantages: ~20 seconds of latency. Limited to 720p resolution.
*For streaming only. Official page.