Fastest Autofocusing Canon lens needed

[AckleyImproved]

Hi

I am after a very fast Auto focusing lens.

I have a 70-200L f/2.8, but I need another to fill the gap.

How does the 24-70L f/2.8 go in relation to AF. Will it be able to focus on a dog running towards you?

Or is a prime lens like a 85 f/1.8 or a 135 f/2 a better option?

This is what I am planning to have in my kit by the years end.

70-200 IS
10-22
24-70L f/2.8
50 f/1.4
either a 85 f1.8 or a 135L f/2

Can you please tell me your thoughts on a quick focusing canon lense for animal action shots!

Thanks
Ackley