I personally would like to see us start with coming up with a strong foundation, something that we can make work against most other similar or slightly larger groups we come across. With the right combination of sustain (for those unfamiliar with WvW speak this just means survivability through healing, invulns, buffs, whatever) and damage I think we could dispose of most similar sized T3 and T4 groups (Mag excluded; don't know how they're down here with us).
That said, here is a more directed line:
How should we deal with the current scourge meta? How do we sustain against a 5 man group that is, say, 3 scourges, a FB, and a SB?
Against such a group, we'll be dealing with lots of condi, a pretty powerful burst class, boon corrupts, a big boon strip, and a healer who spits out resist, stab, protect, and aegis. I wouldn't want to build a group solely to hard counter this but a balanced group that can deal with this, then turn around and deal with a more power oriented group or a more cc/mobility oriented group.