This week Apple highlighted that both its new iPad Air and new iPad Mini With Retina display will have dual band (2.4GHz and 5GHz) 2x2 MIMO WiFi. Dell Venue 8 Pro is now the only 8" Windows 8.1 tablet that has dual band 2x2 MIMO WiFi.
The other three 8" Windows 8.1 tablets announced so far, Toshiba Encore uses dual band 1x1 11n WiFi; Lenovo Miix2 use single band (2.4GHz only) 1x1 11n WiFi; Acer Iconia W4 has not disclosed its WiFi spec, but it is likely to be single or dual band 1x1 11n WiFi as well.
2x2 MIMO WiFi achieves twice the communication speed of 1x1 WiFi, while at the same time provides a much longer range and signal reliability. Also for the new Miracast feature (wireless display) introduced in Windows 8.1, 2x2 MIMO WiFi provides a much better Miracast video quality than 1x1 WiFi because of the speed and signal reliability. As for the communication frequency band, 2.4GHz band is a very "crowded". 5GHz band gives you a lot more selection of channels and is free from a lot of the interferences.
Since WiFi is the only communication medium in most of the tablets, a good WiFi really enhances the user experience whether you are at home, at work, at the airport, or at the Starbucks.