what is the best mod chip for ps2 version 4.

Is any version more superior to each other?

My opinion "Matrix Infinity"
Auto boots all media and fully supports Sony hdd as well as third party hdd.
With newest firmware release v 1.31.
Awesome modchip. Worth every penny!!

The most expensive one.

btw, did you read the mod chip forum? Right at the top. Easy to find.