Which mode is most commonly used for SSB voice communications in the VHF and UHF bands?
Why By long-standing convention, amateurs use lower sideband on 160, 80/75 and 40 meters, and upper sideband on 20 meters and everything higher, including 60 meters and all the VHF and UHF SSB weak-signal segments. So SSB work on 6 meters, 2 meters, 222 MHz and 432 MHz is done on upper sideband. This is operating practice, not an FCC rule, but everyone follows it so stations can hear each other intelligibly.
Watch out Lower sideband is the convention only on the bands below 10 MHz; using it on 2 meters would leave your audio unreadable to stations listening on USB.
LSB below 10 MHz, USB above. VHF/UHF is way above, so it is always upper sideband.