I'd choose good tank/bad healer.
A good tank can set a decent pace to get the instance run over with as quickly as possible, and will likely be able to rotate his cooldowns to make up for some of the healers ineptitude. Hopefully the tank is -nice and patient- enough as well; frustrated tanks usually make runs a little less enjoyable! If we're lucky, maybe there'll be a caster in the group with a cure or physick who can help the healer out a little.
A good tank can set a decent pace to get the instance run over with as quickly as possible, and will likely be able to rotate his cooldowns to make up for some of the healers ineptitude. Hopefully the tank is -nice and patient- enough as well; frustrated tanks usually make runs a little less enjoyable! If we're lucky, maybe there'll be a caster in the group with a cure or physick who can help the healer out a little.