Depends if you wanna learn or just watch
For Tracer, Genji and McCree, if you are interested in learning I would highly recommend Kabaji, he never stops talking, he always tells the viewers what he is doing, why he is doing, what are the pros and cons of this action, why you should consider doing this etc etc.
He plays mostly soldier and tracer but he plays McCree and Genji too
If you just wanna see someone making funny faces watch Kragie, he is a Tracer player and has reached #1 on EU ladder if I am not wrong