A stream site can not have better subs as they do not do subs they just stream someone else's shit. Also in the case of stuff coming out which one is more logical:

Identify group who does good subs for show X and dl show X when they release it.

Wait for any random group to sub show X then wait for someone to dl that groups version of show X and upload it to stream site. Then wait for it to be approved then watch said stream.