I would get the first team to 80th.
And do Wintergrasp and Heroics, with a goal of PvP +10% EXP Shoulders and PvE +10% EXP Chest.
Chances are, the best way to do this will be to solo run your tank through the dungeon finder on a weekend.
And then run your team, with the semi-geared tank, taking 9.1 tier upgrades, along with iLV 200 drops.
And then once you can run a bunch of heroics, do the badge BoA gear.

I went with Cloth - caster stats & Leader - melee stats.
But really, you could get by with Cloth shoulders and Cloth chest, for all toons.
The 20% experience reduction, greatly helps other teams in leveling.
It is two fewer levels of collections in Northrend.
It is dinging 68th in late Terrokar or early Nagrand.

Also an 80th team, can do dailies for about 1k+ gold per day, in about an hour.
You can buy BoA Cold-Flying books, which will make Northrend much easier for later teams.
You can even mail BoA items across factions, to assist any of your teams.



I'd say Levels > All.
But certain BoA's will get the levels faster.

Professions are gold, which is quite nice.
You might prioritize toons to 68th, then professions for passive gold generation.
And then once they're all 68th, gradually work them up towards 80th, playing whichever set has rested.
I'm pretty much doing that now - 3 of 7 sets are 80th, 5 are between 68th and 75th.