I'm a leader~
Everyone in the group knows(unless really new...like added today) that if you have 3+ participations...you have a chance of getting a pack.
First Legendary pack I ever gave was to one of the members who had participated all 5times possible that GNW AND had a huge load of donations/contributions rivaling what I had at the time. Thought he deserved it.
Next week I got 2 Legendary packs. Gave one to myself and gave the 2nd to a different member that had done amazingly by participating all 5 times(like they should to be worthy) and had increased his donations/contributions by a large amount in that 1 week.

I don't always get a Legendary Pack and no one gets to keep getting one weekly.
If another member participates the maximum amount of times and has not yet received one...he/she will instantly be given a Legendary Pack after that GNW.

If members that have received one before are the only ones eligible(max participations) then I choose the 1 that has received the least Legendary packs to get 1.

I keep my own list of people and their alt accounts as well as their activity rate(helpful in group/chat, donations/contributions, participation in GNW). So after the legendary pack is all done I move on to the others.

I don't bother with anyone who only participated 2times. Sometimes I don't even give everyone who participated 3times a pack. These people are put on a list to where I bump them up a level the next week.
Would have gotten nothing = get a pack
Would have gotten 5pack = 8pack
Would have gotten an 8pack = Legendary Pack(this one sadly hasn't happened lol)

So basically...I try to keep it fair. Though it can get harder to do so, but as a leader it's the right thing to do.
If you participate you will be rewarded for your help in the GNW.
If you don't want to participate then you don't get rewarded and I have more Packs to give out to others that do want them :D Easy as that.

Legendary pack is something I don't try to get for myself...because I prefer it to be a reward to those members that try harder than anyone else. I prefer getting the 8pack of seals lol though I have given myself a 5pack before...I missed a few rounds of the ninja war...ended up with 3/5participations.

Even had members saying I should have taken the Legendary Pack anyways because I'm the leader...that's not right though! lol