Along with Ratsmah and Kripp (also on this list), Rumay "Hafu" Wang is an illustrious Hearthstone Arena player whose consistent ability to rack up double-digit wins is worth a follow all on its own. Hafu's staccato delivery and lively demeanor bring the stream to life with a nice tempo, and her moment-to-moment judgements are typically spot-on. Beyond that, Hafu's got an endearing honesty in the way she plays: sometimes she'll start complaining about an opponent's total bullshit win, only to start giggling at her own awful luck.
Hafu's also a good Arena watch because she doesn't latch onto orthodoxy in her approach to the game. She doesn't measure card value as a static qualitative thing – she judges based on what fits into her deck and what'll get her the most efficiency in the long run, even if the card is usually seen as garbage.