I have three main sites where I'm currently focusing my streaming. Why 3? I'll go into that under each one!
Mixer is currently my primary home where I get most of my audience. Having worked there, I built an amazing support structure with that community. There's also almost no delay there, so you're seeing things in real time. On top of that, the interactive features let my viewers directly interact with my stream. This site is why I sing songs and get silly.
Twitch is where most of my friends stream or view game content. I'd LOVE to build my audience there, as the growth potential there is huge. Sadly, their affiliate program requires exclusivity of content, and I'm not prepared to offer that yet. But if you have a twitch account and are looking for some good content, I never stream to Mixer without also streaming to Twitch. Keep in mind that the chat is delayed a little there.
I'm still uploading to YouTube, as that's where many of my fans might have the easiest access to me. I'm streaming there periodically to ensure those subscribers know I'm still putting out content. The drawback is that they are more strict with content control, so if I feel anything might trigger the ContentID system, I might not stream to YouTube for that show. Still, it's an easy way to unify my viewership for both produced and live content if that's your platform of choice. I do sometimes miss messages from that site, however.