With gear levels as they are, the quickest valor-per-minute is a heroic scenario. Additionally, once you cap one character, all other characters on that server receive the Valor of the Ancients buff that will increase valor obtained by 50%.
With your characters:
- Spam heroic scenarios with your main until you cap. If your DPS gear
is near or equal to your tank gear, DPS will most likely be faster.
Most groups are geared enough to easily achieve the bonus objective
that will award even more valor.
- Once capped, repeat with your alts.
The main drawback of this method is having to find two other people to queue with you for the heroic. (On my server, it isn't very difficult; if it is, oqueue is a common solution.)
If this isn't doable for some reason, then spamming heroic dungeons with your main is most likely your best bet due to the low tank queue times. Once capped, then standard scenarios (which don't require two other people to queue) offer a better valor-per-minute value for DPS due to long DPS queue times.