Exactly which app do you plan on using for streaming?
They will differ in their ability to use multiple threads.
Some want a dual core cpu @2.8 or higher.
Others want a i7-2600 or better.
The FX 8xxx chips do well with the apps that can run 8 threads.
The intel i3 dual core chips do well with those that want fast cores.
If price is no object($300), a i7-4770K with a conservative OC would be the best.
For your particular app, find out what the minimum and recommended specs are, and go from there.