ZyXEL, founded in 1989, is one of the popular manufacturers of both wired and wireless routers. They are straightforward and easy to configure, and tend to have very good performance quality.
ZyXEL routers are generally fairly easy to configure, but their port forwarding section is a little more demanding. They usually refer to the port forward as a NAT/SUA Server, which can be a little confusing. You must also make sure SUA Only is marked and if it isn't you can not setup port forwarding without making a major change to your network. Generally speaking this is not an issue and you should have no problem configuring your router.
If you cannot find your exact router in the list below, try following one of our ZyXEL Prestige623 guides. That should get you an open port on pretty much any ZyXEL router.