Confused – Need help

Hi, I am new to Kodi. I have read the posts “START HERE – Pick the Right Kodi Box (updated May 2017)” and “Xiaomi 4K HDR ‘Mi Box’ (Android TV set-top box),” along with a few other posts. After reading them I am more confused than when I started as to what buy.

I am looking for a box to run Kodi. I already have a Roku for many other apps. I have done some searches on the S905(x) boxes recommended here. There are many choices. I am familiar with computers and have built several. I would like to know what to look for regarding things similar to building a computer, processor (I’m guessing the S905(x)), memory and things like that. I would like several choices as to what to buy. I live in the USA and would prefer to purchase from Amazon (preferably not a 3rd party, unless recommended), ebay (recommended seller), newegg, or local retailer store. To me computers are so much easier. Thanks. Rob