Darth Vader vs Darth Bane vs Darth Malgus

A classic

Spoiler:

indeed a classic. tough one, very tough, but gui gon wins

FE Malgus>Revan Reborn>>SF Malak>>Exar Kun>Pre prime Plagueis~Ragnos>>>>>Bane~TPM Kenobi>Vader

Vader

Hard to tell... siding with bane

It comes down to Onslaught Malgus and Vader. Vader probably has more raw power but Malgus is just as ruthless, should be skilled enough to match him and has lightning that even as of his Deceived self could one-shot powerful Jedi like Aryn Leneer. That said, Vader was able to counter the likes of SK's, so unless Malgus disarms him, I don't think lightning will help much. 

Leaning Vader, albeit in a close fight.

Probably Malgus or Vader

Vader's TFU scaling and feats blow Bane out of the water, that leaves Malgus who is hard to compare, based on scaling and overall kinetic output Vader wins via force push spam

Vader

Malgus or Vader

Vader

Either way I think Vader's out if he fights either of them for a decent amount of time. One of the few things I agree with Jensaarai1 on is that Vader's not prepared to deal with other strength based duelists. 

The thing that balances this out is that Vader will probably try and let the other two finish each other off first. 

Honestly I may back Malgus.

Vader

Bane