If you want to learn to speak english well, watch those programs that use English properly. Blackadder. Archer. Sherlock. Even some of the marvel movies (GOTG) are very careful in how they pronounce and articulate words. Then watch every Brian Cox and Attenborough documentary. You might come out with a bit of a British accent but that is far far better than any youtube-derived accent. Better you sound like Stirling A…
So you're equating using English "properly" with British (specifically, English) English? From a linguistic point of view, you couldn't be more wrong. No variety of any language is superior to another
Not variety or accent. These shows use words carefully. They speak in exact meanings. The use a wider vocabulary and do not blur words. In fact much of their humor is based on misunderstandings rooted in pronunciation. Archer makes jokes about furriers and farriers. Blackadder about the formal name "Captain Darling" and the pet name "my darling", forcing the listener to maintain an understanding of context. These tricks aren't used on The Simpsons or the Big Bang Theory, shows largely aimed at lowest common denominators. Such differences are irrespective of accent or dialect.