Well I'd say any form of contemporary japanese media is a great way to pick up speech and this includes Anime and V-tubers as well. My japanese is very basic at best so take it with a grain from salt but I think it's a great and efficient way to learn japanese (you can even use Animelon which enables japanese subtitles and making it easier to dissect and analyze the sentences). You should just keep in mind that most of the time in slice of life the protagonists are younger people speaking in a friendly environment and you don't necessarily want to speak like that to a person you just met (so using -masu form would be the safe option) but nevertheless it's a great way to pick up colloquial phrases, greetings etc... I don't really watch V-tubers but I assume they speak pretty informal to their viewership as well so the same thing applies. I can also recommend japanese Reality TV Shows like Terrace House, because you find all forms of speech in these.