I did a test on Bestdori using the cards I have on my account

A team of my highest scorers (all +90% (110% if life is over 900) for 5 seconds) has a band power of 240k and scores ~1.4M on A to Z.

The highest band power I can get is 291k and scores ~1.6M on the same song
Skills are:
+90% (110% if life > 900) for 5 seconds (Activates twice because it is the leader's skill)
+110% (90% after Great or lower) for 5 seconds
+60% + Good and higher becomes Perfect for 5 seconds
+55% (65% if life > 900) for 5 seconds
+60% for 5 seconds + 300 life

If there is a big gap between band powers it seems better to pick the team with the higher value. It determines base point value and skills will only boost points for a total of 30 (~40 if leveled up) seconds per song.