The Worst ones
“Kill an enemy Scorpion/Wraith”
This challenge requires Many, many things to line up and depends entirely on the enemy getting a Tank, something that any player would rather prevent, unless they have this challenge. Tanks rarely ever spawn in BTB, Spawning a tank requires the game to progress to the last round as far as I can tell, think 2 out of 3 flags/total control rounds/powercells drops each team having won and lost 2 rounds each. This almost never happens. The majority of the time BTB goes to the last round it’s because one team is rolling and so such rounds pass far too quick for anything to spawn. When teams are equally matched BTB matches will rarely pass the first round let alone reach a mutual game point.
If Big Team Heavies were part of the rotation this wouldn’t be a nearly as big a problem.
“Kill # players with a Scorpion/ Wraiths main gun”
This also falls into this, category for much of the same reasons as the first example. Except instead of letting an enemy get the tank your now competing with 23 other players to be the one inside the tank.
“Stop an enemy killing spree”
This is slightly less egregious as it’s far more likely to happen but it still depends entirely on an enemy player getting a killing spree and you being the one who kills him. This is incredibly hard to do on purpose and will only really happen on accident which makes it bad. The reverse of this “earn killing sprees” is an example of a good challenge as it’s something a player can actively try to do.
“Play/Win Game mode”
“Get Kills with Weapon”
Thus far this is where the “Play/win a Gamemode” and with the exception of AR and Sidekick, where “Get kills with Weapon” challenges go. Players trying finish these challenges are stuck relying on random chance. Will the map spawn the weapon they need? Will the game mode be the one they want? The weapon challenges are worse for a players teammates as that player will trend towards using that weapon even in situations where that weapon is bad, leading to players who are trying to win to complete their challenges stuck with teamates who are doing less than their best, or even their average.