To check how your WiFi performs, you should open your terminal and paste the following:

/System/Library/PrivateFrameworks/Apple*.framework/Versions/Current/Resources/airport -I

This will print out a screen similar to this one:

     agrCtlRSSI: -54
     agrExtRSSI: 0
    agrCtlNoise: -97
    agrExtNoise: 0
          state: running
        op mode: station 
     lastTxRate: 144
        maxRate: 144
lastAssocStatus: 0
    802.11 auth: open
      link auth: wpa2-psk
          BSSID: f9:77:99:2d:3d:60
           SSID: name
            MCS: 0
        channel: 11

You want agrCtlRSSI to be as low as possible (up to - 55 things are great) and agrCtlNoise to be as high as possible (-120 is the max).

I've had a lot of issues with figuring out the strength of different WiFi connections in my coworking space, and this did the trick. I hope this helped you discover which WiFi network is performing the best for you!