Tube amp - which speaker tap to use?

Jolida 302b w/ 4 ohm or 8 ohm speaker taps paired w/ Focal.JMlab Chorus 714s speakers (91 dB - 2.83V/1m) with a nominal impedance of 8 ohms but a impedance of 4 ohms.

Which tap should I use and why? Can I try both and just use the best sounding or is there a technical reason to use one or the other?

Thanks.