>>277057649
An i7 as a minimum the latest generation of it if you can. Nvidia GTX 970 at the MINIMUM for a video card. A motherboard with a fuck ton of USB port if possible get one with USB 3.0 and USB 3.1 connections and USB-C connectors.

Then buy a Rift-S if you are strapped for cash. An Index if you are not strapped for cash.
An Oculus Quest with the Oculus Link cable if you want portability option as well as wireless (medium price option).