Darth Maul vs Darth Tyranus vs Darth Vader

The three apprentices face off.

Battle ground: The Emperors Throne room

Everyone standing equely spaced

Round 1 Legends only

Round 2 New canon only

Round 3 all feats from all continuities

Vader, Vader, and more Vader.

Very original
Maul slaughtered by either of the other two every time,
Vader and Dooku engage in a lengthy fight leaving Ani the victor 9/10

Vader in all

Overall Vader's the most Powerful. Then Dooku, then Maul.

But Dooku can take some wins against Vader, and Maul can take some against Dooku. But Maul would be lucky to win even 1 against Vader, because the Power gap just gets too big by that point.

Vader.

Canon Maul wins.