Honestly, GrappLr is the most entertaining of the bunch for me right now. MajiinBae takes the cake when it comes to entertaining competitive streaming.
Aside from that, if you like high-level play, I recommend Alan. SirturmundLOR and Aikado are also worthwhile watches.
Oh, and JinxDidNothingWrong is starting a cool following as well :)
Please, move the comment box to the right after the main post. I think Kbin would have a lot more engagement if people didn't have to scroll all the way down to the bottom of the page in order to post something.