In my group, what i do is that the legendary pack follows a rotation system. so if u get a legend pack this week u can't get another one until all members get a legend pack. but of course it will only be rotated to those who participated in the war. For the hero and elite packs, I based it on their war participation times. If there is a tie i compare their weekly donations. What usually happens is that almost same players get the hero and elite every week. I think this is a good system since everyone will eventually get a legend pack, u just have to participate in the war. and for the hero + elite packs, giving it to members who make a difference is more important than giving it to casual players. Since those casual players have higher chance of quitting the game than those who spend many hours on the game. So basically, it is a good investment too to give it to those highly active members.