Is counter attack a matter of anticipation or reflexes?

Both anticipation and reflex are important but I think reflex is more important specially if you have an opponent who is smart enough to read every play set-up you are trying to make. 

Q: How can you train your reflexes?

A: By training table tennis.

Q: How can you improve your anticipation?

A: By traning table tennis.

If you think about the best blockers in the world, those who seem to be able to act in a parallell universe and as Adam Bobrow commented 'he could been drinking a cup of tea right now!' they are often shorter and younger players.

This give two advantages, the nerve signlas has a shorter distance to travel between the brain and the hand and younger person has faster reactions compared to older.
A short table tennis player can (and needs) to play closer to the table compare to a really call one due to longer distance between brain and hand. But since taller players have a greater 'wing span' they can make up for this disadvantage in reaction time.

Example of player with great reflexes - Koki Niwa 1,62m

Example of player with great anticipation - Jan Ove Waldner 1,79m

@inyagan 

Definitely!

But I just feel like training for a counter attack should be done in two ways:

(1) Reflex (Multi-balls training) 

(2) Anticipation (Understanding the physics of things)

If someone flicks a heavy backspin serve, there is a high percentage than its going to land in the forehand side of the server. 

Both plays a role in a successful counter attack but it got me thinking if one weighs more than the other.

I like your idea with reaction traning and taking the player out of the comfort zone speedwise. Likely it will help the player to cope with balls in 'normal' pace easier. Make them learn to relax and not panic and stiffen up.

This is where table tennis has similarities with martial arts, relax, explode, relax again.