There won't be a 'best.' There will be what works in a given situation, and the thing that will work more often than not, vs the teams you play.
So, Hyperbelle Kuzzman probably won't work, but if you can manage to hunker down and get a blitzfaust out. It'll be hard to stop.
Lichtbogen works great....unless the enemies know how it works, then it isn't the best.
Aneska....Well, her guns are crazily different playstyles. So, you kinda got to card around them.