1.4 TC

I'm a little confused on which 1.4 TC to purchase. If I want to use with a 70-200f4 (and maybe later with 400 f5.6) lens (on 50D), and I'm concerned about the list below in the priority of what's most important to me, which one would you purchase? Also, if I wanted to stack two, would you recommend using the same model or two different models?

1. IQ
2. AF
3. Reporting