Downloading the game on PC unlocks features you won't find anywhere else:
The PC version is famous for its mods. Sites like GTA5-mods.com allow you to add everything from realistic cars to superhero powers.
Experience Los Santos in 4K resolution at 60 frames per second (or higher) on high-end hardware.
Historically, platforms like Epic Games have given GTA V away for free during special promotional periods. It is worth keeping an eye on their "Free Games" section for future events.