I'd do it with an HDMI cable assuming that option exists. Wired is better than wireless for audio quality and problem-free performance, although wireless has been catching up over time.
I use a BlueSound Node to stream high bitrate audio to my sound system, and it can work via Bluetooth, Wifi or a wired connection, or combinations of those. I found the wireless connections a bit less reliable while the wired connection is consistently better sounding and 100% reliable.
However my results are with decent quality tower speakers; the audio quality with a soundbar may not be high enough to distinguish any audio quality difference between a Bluetooth or wired connection.
BTW, while Bluetooth and Wifi are both wireless technologies, the quality of your Wifi is a non-factor in how well a Bluetooth connection will work in your house (unless there's some arcane interference issue, which seems extremely unlikely).
