Change the search rankings for uploaded videos
Currently the search rankings reflects that of the live content: view count. While this works for live content to an extent, it hampers the growth of the uploaded content. Youtube works on a method of keeping viewers locked into its site by funneling people down a tunnel of interesting and related content by keeping the content fresh, and if Twitch relies on this same method, it will end up with old, high view count content staying on the top and new, fresh content falling below the line, never to be seen. Twitch needs to use a similar, but unique, method of favoring fresher content that also rewards its creators for working hard.
I would caution to avoid directly copying Youtubes methods as it's moved itself down a dangerous spiral of "drama building content", and would suggest alltogether avoiding a thumbs up/thumbs down ranking system. Instead, I'd suggest that the new search algorithm focuses on this: Channel follower count, Average minutes watch, total minutes watched, comment/view ratio. Additionally, all viewing options should add in some recommendation options to keep people going further down the rabit hole of content on twitch.