For a desktop machine you can use internal cards or USB. USB is simpler and cheaper but you cannot run mimo on most because it requires multiple antenna. If your router does not do mimo then might as well use a USB adapter and a long USB extension cable so you can locate it in a optimum location which may not be behind your machine.
The internal adapters cards that have multiple antenna are you best bet for performance. some come with short cable to allow you to position the antenna.
In any case you are going to have some issues. Wireless signal is optimized on most routers to flow horizontal. signal going up and down is not as strong..in fact some routers have a dead spot directly above them.
Still wireless is not recommended for gaming. Games don't use a lot of bandwidth but require a nice steady stream of data. Other people using the router in your house or any form of interference will cause packet loss. Unlike normal programs games do not retransmit loss data. You get too much loss and the game gets lag spikes while your machine and the server figure out how to get back in sync.
You may be better of with a powerline extender for gaming.