Faithful witness vs pioneering 

One foundational question is whether the great commission can be completed (or was intended to be).
Most people I encounter don’t actually answer that question with a firm yes or no. They tend to lean one way or another.
Based on how you lean, you balance two ideas: faithful witness in the communities where the church presently is vs pioneering evangelism into places where it is not.
The reality is there is a need and role for both. Churches, however, are tempted to favor none over the other, and most often I find they are tempted to favor faithful witness.
Pioneer evangelists, apostolic types, who focus ministry on people outside the church, are less common. And, because they are taking resources away from the church members, they are often less favored and encouraged.
I look for church leaders who actively encourage the apostolic and pioneering types, who support their efforts “against the grain” while at the same time enabling and encouraging faithful witness. It’s a difficult balancing act.