Doombawkz
Trust me, I'm a doctor
Ruthless provides huge damage potential at the risk of some health, and also allows you to use strings that involve ferra, meaning more reach or priority on some normals and strings.Eh? One has increased mobility and presumably something else, another get to keep some Ferra moves (I assume) and sacrifice move. I think @Doombawkz knows more.
Lackey on the other hand lacks the reach/priority and damage buff, but gains other benefits such as some natural armor. His strings change a bit due to the lack of Ferra's assistance, however he also gains the benefit of not having to wait for her in order to press his effectiveness. He literally becomes a one-man-army, being capable of some mobility and options the other two simply won't cover.