I don't know why you would watch anime on Youtube of all places. The quality is always horrible, I watched about 3 episodes of AOT on Youtube before switching to literally anything else.
The quality is really good on official broadcasting channels. Muse asia and ani one asia provide quality content
Muse Asia only gives you 720p. Maybe it would look good on a bad screen. But if you have a good monitor, then going full screen will make your eyes regret ever watching anime on YouTube. I get the whole idea of supporting the creators, but quality is quality. You cannot deny that Muse Asia's 720p episodes look like trash on a good monitor.
When you use a mobile or an iPad to watch those episodes on YouTube, it looks godly compared to others
It looks better than pirate sites? Nope. You're wrong about that. Here's how it goes
Torrents > Official streams > Illegal pirate streams > YouTube. No matter what device you're in, that's the order. I've uploaded videos on YouTube before and they lower the quality of your video. If you compare an anime episode from YouTube side by side with an anime episode from a pirate site (a good one with a good video hosting service) then the difference is easy to spot if you have somewhat good eyes. Most dark scenes come off as pixelated on YouTube. Back in the day, I watched a handful of anime on YouTube, the quality was almost never good. Ani-One Asia at least tries to keep the quality good, but it still doesn't look good. I'm sorry man but pirate sites (good ones) are just better.