Good System For Gaming/Streaming/Video Editing

Here is the list:

PCPartPicker part list / Price breakdown by merchant

CPU: AMD - Ryzen 7 2700X 3.7GHz 8-Core Processor (£269.94 @ Aria PC)
Motherboard: Gigabyte - X470 AORUS ULTRA GAMING ATX AM4 Motherboard (£127.99 @ Amazon UK)
Memory: Team - T-Force Vulcan 16GB (2 x 8GB) DDR4-3200 Memory (£149.99 @ Overclockers.co.uk)
Storage: Crucial - MX500 500GB M.2-2280 Solid State Drive (£90.38 @ Amazon UK)
Storage: Seagate - Barracuda 2TB 3.5" 7200RPM Internal Hard Drive (£50.39 @ Aria PC)
Video Card: EVGA - GeForce GTX 1080 8GB Superclocked Gaming ACX 3.0 Video Card (£495.46 @ Amazon UK)
Case: Fractal Design - Define S ATX Mid Tower Case (£65.74 @ Ebuyer)
Power Supply: EVGA - SuperNOVA G3 750W 80+ Gold Certified Fully-Modular ATX Power Supply (£84.99 @ Ebuyer)
Monitor: Asus - ROG SWIFT PG248Q 24.0" 1920x1080 180Hz Monitor (£358.80 @ Aria PC)
Total: £1693.68
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2018-07-15 10:24 BST+0100

Better quality components.
500W PSU will not be sufficient. Minimum 650W required but it is better to get 750W for OC.
G-Sync monitor included to give you better gaming performance.