While there is a difference in performance pretty much all wi-fi products won't exceed the bandwidth cap provided by the network provider.
For example, my network cap is somewhat low (725KBps) but my cheap $30 USB receiver can communicate at well over 2MBps (2048KBps) down TWO levels to the base receiver so I'm well over that.
For VIDEO it's a different story. I was going to stream movies from a drive up here to my media receiver but this proved insufficient so I went back to using the ETHERNET cable for that.
My Bell Gateway was also bottleneck so I bought my own ROUTER (and MODEM) to sort out streaming video. I actually have ETHERNET from top-floor to basement and wi-fi for twenty feet. I wanted to go wi-fi only but the really good wi-fi USB adapters were both expensive and not on the approved list form my Western Digital device (PC's have no such issue in general as drivers are supplied).
Wi-Fi signal strength:
1. Drops off by distance
2. Drops off by obstruction
3. won't matter if network bandwidth is lower
4. Can vary by the wi-fi receiver
*So unless you have bandwidth requirements that require a good solution, just go buy a $30 USB adapter rather than a more expensive PCIe device with triple antennae etc.