I suggest that plunder rating be changed from total plunder to net plunder. This is prompted from a trend I see from 2-3 cooperating guilds: They plunder an apposing city with one account, then plunder back and forth between accounts multiple times. This inflates their "rating" and also prevents you from catching up with the resources to try to retaliating to get it back as it has now moved across the map. They can plunder 10 million, lose 9 million to being plundered, and be rated as 10 mil total plunder rather than 1 mil net.
Even better would be to additionally subtract the cost of the troops used to do the plundering.
If the game is going to have such a ranking, I would just rather see it try to be made meaningful, not just a number people are artificially inflating like the old prestige farmers, and granted, it is only to 3 people per week, but you are giving a reward out to people who are artificially inflating the number.