If you are far from the router you will not find a card that will work well for you for anything that is either bandwidth or latency sensitive (so streaming videos or gaming). The wireless speed you get quoted is just marketing, 300Mbps wireless usually doesn't even hit 100Mbps right next to the router.
You need to extend your wireless radio signal by using an access point that is connected to the router by an Ethernet cable (first choice) or a pair of AV1200 powerline adapters (2nd choice).
If you don't really need the wireless (i.e. you don't have a laptop or want wireless for phones, etc.) then just use an Ethernet cable or a pair of powerline adapters without the access point.