What is the hardest badge to achieve and what is your most proud badge you've obtained?

I just recently got my 20 kill badge last night on Horizon for the first time and thought what have been your most accomplished badges you've obtained?

After looking at all of the badges, it seems like 10 kills for each teammate would be extremely difficult to obtain, literally killing half of the lobby is a crazy feat and of course the predator badge is definitely up there on the difficulty scale.

Also, here's a video of the 20 kill game: Horizon 20 kill Video!