Toms Hardware has some pretty great rundowns of the CPUs and such - There are many ways to skin a cat, so start with what you would like to have- even a ready made computer like a alienware or asus - and compare those components... Using "Compare" and "Benchmark" and "Review" along with the product name in google or youtube can help you find similarly competitive products that are close in price and specifications...
I only offer this because it seems like you may not know exactly where to start. i3,i5,i7 all have specific designs and costs associated... It can get a little deep pretty quick... best to scour the web and glean what you think is the best information for your own use...
This method is how I figured out that I should buy
this laptop. After all my comparing and sniffing around- I was confident when I found it was said among many reviewers to be a nice value for someone who wants out of the door @ $1300... Got it last month- Maybe you can find a better one for cheaper?!
I don't know much about streaming, but it seems like your computer can be smoking (Good) but if your internet isn't Da Kine (Quality)- Streaming is not gonna be a fun time.
Hope this helps!