Round 1: Bryan Mills is an all around good operator, a Jack of All Trades that has a specialty in combat. He's nowhere near the level of John Wick is a straight up fight, though. On top of which, by the time of Taken, Mills is old. 9.9/10 to Wick.

Round 2: Nolan Ra's is not immortal, and not that impressive. Kai can move at incredible speeds, being able to keep up with Tengu. His sword is OP, and he is more than skilled enough without the special sword and Tengu abilities already to beat Ra's. 9/10 to Kai.

Round 3: Neo in real world will get beaten fairly easily by Qui Gon, 10/10 for Qui Gon. In Matrix, Neo is leagues above Qui Gon, 10/10 for Neo.

Round 4: John Constantine has nothing on Zeus. Constantine is powerful with prep time and his sharp wit. Both are not very useful against Zeus. 10/10 Zeus.

None of these rounds are really close. Rounds 1 and 2 would be the most entertaining to watch, but unless there's other circumstances involved, both are fairly one sided.