The decision will be based on what kind of traffic do you intend to send to PC3?
If you are only interested in say the web port 80, then portforward is a better option. However, if you want to run a full Nmap scan on interesting ports with service fingerprinting, then route is the option for you.
Basically, if your activities on PC3 only concern a single port, port forward. If they need more ports, route.