I have what I think is a fair compromise between those who desire to quit games they've lost, and others who want those people to stick it out to the bitter end.

Right now, the winning team is almost certain to scoop up most of the favor categories. If you get the most kills you usually get the most gold, and if you get the most gold you usually get better items (which lets you get more kills), which lets you get more flag captures, which lets you upgrade your citadel faster, etc. The solution is simple: split up the categories between the winning and losing teams. Give both the winning and the losing team a "most kills" award. The winning team would still get the +100 bonus or whatever it is for winning, so they would get more favor overall. If a player quits, he or she gets no favor. That way, there is a real incentive to stay in the game.